United States of America v. Sunny Sok

PRECEDENTIAL
UNITED STATES COURT OF APPEALS
FOR THE THIRD CIRCUIT
No. 23-1939
UNITED STATES OF AMERICA,
v.
SUNNY SOK,
Appellant
Appeal from the United States District Court
for the Eastern District of Pennsylvania
(District Court No. 2-19-cr-00348-001)
District Judge: Honorable Mitchell S. Goldberg
Argued on June 4, 2024
Before: HARDIMAN, PORTER, and AMBRO, Circuit
Judges
(Opinion filed August 22, 2024)

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Abigail E. Horn (Argued)
Federal Community Defender Office for the Eastern District
of Pennsylvania
601 Walnut Street
The Curtis Center, Suite 540 West
Philadelphia, PA 19106
Counsel for Appellant
Anita D. Eve
Robert A. Zauzmer (Argued)
Office of United States Attorney
615 Chestnut Street
Suite 1250
Philadelphia, PA 19106
Counsel for Appellee
OPINION OF THE COURT
AMBRO, Circuit Judge
A Philadelphia police officer pulled over Sunny Sok
after he made an illegal right turn. The officer ran a search and
discovered that the vehicle had an expired registration and also
that Sok had an arrest warrant for a probation violation. The
latter turned out not to be true—the warrant was no longer
active—but before that came to light, the officer arrested Sok.
While the officer was doing so, he claimed to smell marijuana

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emanating from the vehicle, which led him to search it. The
officer discovered multiple narcotics and a firearm, and Sok
was subsequently charged with possession with intent to
distribute a controlled substance, possession of a firearm in
furtherance of drug trafficking, and possession of a firearm by
a felon.
Sok moved to suppress the physical evidence seized
during the search. The District Court determined that the
officer’s testimony regarding the marijuana odor was not
credible and, consequently, that there was no probable cause
for the search. The Court went on, however, to conclude
suppression was not warranted because the narcotics and
firearm would inevitably have been discovered under
Philadelphia’s Live Stop Policy, which requires that
unregistered vehicles—like Sok’s—be impounded and their
contents inventoried.
On appeal, Sok argues that the inevitable-discovery
doctrine does not apply and the evidence should have been
suppressed, as the Government has not demonstrated that any
impoundment of his unregistered vehicle would have been
lawful or inevitable under the Live Stop Policy. But Sok failed
to raise these suppression-related arguments before the District
Court. Thus, we cannot consider them unless he shows good
cause for us to do so. Fed. R. Crim. P. 12(b)(3)(C), (c)(3); see
United States v. Rose, 538 F.3d 175 (3d Cir. 2008). Because
he does not make that demonstration, we do not consider his
untimely arguments and affirm the judgment of his conviction
and sentence.

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I. Background
Philadelphia Police Officer Joseph Mason pulled Sok
over for making an illegal right turn in April 2019. Officer
Mason ran the car’s license plate in police databases. The
search showed that the vehicle had an expired registration. It
also showed that the owner of the vehicle, Sok, had an arrest
warrant against him for a probation violation. In fact, there
was no outstanding warrant, as Mason learned later in the
encounter. Before that, however, Mason confirmed Sok was
the owner, asked him to step outside of the vehicle, informed
him of the outstanding warrant, and placed him in handcuffs.
As Sok stepped out, he told Mason that the warrant was no
longer active and told him to call his parole officer to confirm.
As this occurred, Mason saw two small bottles in the driver-
side door pocket that “contain[ed] a purple liquid.” App. 99.
He believed the substance in the bottles was Promethazine
syrup, a type of cough syrup that is a controlled substance.
This too turned out to be a mistake. The purple liquid in the
containers was later tested and was not a controlled substance.
Sok continued to ask Mason to call his parole officer to
confirm the warrant was no longer outstanding, but Mason
proceeded to detain him. He frisked Sok and discovered two
other small containers on his person, including a pill container.
Mason then placed Sok in the back of his police car. He went
back to Sok’s vehicle to obtain the two small bottles from the
driver-side door. As he was doing so, Mason claims to have
smelled an odor of marijuana coming from the vehicle. This
was notable because he had not smelled marijuana on his first
approach. Based on the alleged marijuana smell, Mason
searched the car.

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The search revealed, inter alia, a large bottle with a
label reading “Promethazine”; two more small bottles
containing purple liquid, similar to those in the driver-side
door; a bag of white crystals and powder; a plastic soup
container containing a green leafy substance; a second soup
container holding a bag of pills and white powder; and a
revolver. The various recovered substances were later tested.
The green, leafy substance was marijuana, and some of the
containers held marijuana resin. The remaining items included
a number of controlled substances, including heroin, fentanyl,
and methamphetamine. But none of the small bottles
containing the purple liquid or larger bottle labeled as
“Promethazine” held a controlled substance. After Mason
discovered the narcotics and firearm in the vehicle, he received
confirmation that Sok’s probation warrant had been lifted and
was no longer active.
In light of the narcotics and firearm, Sok was indicted
on charges for possession with intent to distribute a controlled
substance, 21 U.S.C. § 841(a)(1), (b)(1)(A), possession of a
firearm in furtherance of a drug trafficking crime, 18 U.S.C.
§ 924(c)(1)(A), and being a felon in possession of a firearm, 18
U.S.C. § 922(g)(1). He filed a motion to suppress the physical
evidence seized during the stop, arguing that the officer
impermissibly extended the stop and there was no probable
cause supporting his arrest, meaning the seized evidence
should be excluded under the fruit-of-the-poisonous-tree
doctrine. See Wong Sun v. United States, 371 U.S. 471, 488
(1963). The Government opposed, arguing that the traffic stop
was valid, reasonable suspicion existed to extend it, and there
was probable cause to search the car, based in part on Mason’s
detecting an odor of marijuana coming from it. The District
Court then held a suppression hearing.

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During the hearing, Mason, in addition to discussing the
details of the traffic stop outlined above, also testified about
Philadelphia’s Live Stop Policy concerning the impoundment
of vehicles. He described how, had he not searched the car
during the traffic stop, he would have impounded it due to its
lack of valid registration and thereafter would have conducted
an inventory search per the Policy.
The Live Stop Policy in effect at the time stated that
“any vehicle may be impounded when it is determined, during
a lawful vehicle investigation[,] that the operator is in violation
of any or all” of four Pennsylvania state statutory provisions,
one of which prohibits driving an unregistered vehicle. App.
241; see 75 Pa. C.S. §§ 1301(a) (“No person shall drive or
move . . . any vehicle which is not registered in this
Commonwealth unless the vehicle is exempt from
registration.”), 6309.2(a)(2) (“If a motor vehicle . . . for which
there is no valid registration . . . is operated on a highway or
trafficway of this Commonwealth, the law enforcement officer
shall immobilize the motor vehicle . . . or, in the interest of
public safety, direct that the vehicle be towed[.]”). Despite the
permissive “may” language quoted above, the Policy later
states that any vehicle in violation of the registration
requirement, 75 Pa. C.S. § 6309.2, “shall be impounded”
according to the procedures set out in the Policy (with limited
exceptions not applicable here). App. 242.1
1 A newer version of the Policy, effective as of February 18,
2022, provides that, “[i]n accordance with Pennsylvania case
law, only vehicles that bear a public safety risk may be subject
to immediate towing (impoundment).” Philadelphia Police
Department Directive 12.8, “Live Stop” Program,

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Under the Policy, once it is determined that a vehicle is
unregistered during the course of a traffic stop, the officer
must: (1) confirm the registration status over police radio; (2)
inform the operator the vehicle is being impounded; (3) prepare
the relevant report; (4) respond to other priority calls; and (5)
after the tow truck arrives, complete an inventory search.2 If
the registration status of the vehicle cannot be confirmed, the
vehicle will not be impounded. If the officer needs to leave the
scene prior to arrival of a tow truck, such as by responding to
a priority call, then the tow truck will be canceled. If the tow
truck does not arrive within 30 minutes, the officer will simply
issue a citation rather than tow the vehicle.
After the suppression hearing, the District Court
ordered supplemental briefing on multiple issues, including
whether Mason’s search of the car would have been legal if the
Court were to disregard his testimony regarding the marijuana
odor as well as how the Live Stop Policy “impact[ed] the
legality of Officer Mason’s search[.]” App. 186. In his
supplemental brief, Sok argued that there was no probable
cause for the search because Mason’s testimony regarding the
marijuana odor was not credible. He also asserted that the Live
Stop Policy had no effect on the legality of the search because
https://www.phillypolice.com/assets/directives/D12.8-
VehicleOrPedestrianInvestigations.pdf, App. A at 2 (last
accessed August 20, 2024) [https://perma.cc/88EJ-ATWC].
This caveat was not present in the Policy at the time of Sok’s
arrest, however.
2 Here, there is no dispute that an inventory search of Sok’s
vehicle would have occurred after an impoundment under the
Policy. There is also no dispute about the legality of the scope
of the potential inventory search.

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Mason did not actually “conduct a proper ‘live stop,’” so
“neither the inventory search exception nor the inevitable
discovery exception to the Fourth Amendment’s Exclusionary
Rule apply.” App. 197 (citations omitted). The Government
responded that Mason’s testimony regarding the marijuana
odor was credible and supported probable cause. It also
claimed that the Live Stop Policy would inevitably have led to
the discovery of the incriminating evidence because “the
controlled substances and firearm would have been discovered
when officers conducted an inventory search of the vehicle
pursuant to” the Live Stop Policy. App. 211.
After reviewing the supplemental briefing, the District
Court denied Sok’s motion to suppress. It first concluded, in
Sok’s favor, that the warrantless search of his vehicle was not
supported by probable cause because Mason’s testimony that
he smelled marijuana emanating from the car was not credible.
But the Court nonetheless ruled that suppression of the
physical evidence was not warranted because the inevitable-
discovery doctrine applied. Specifically, it determined that
even if Mason had not searched Sok’s car during the traffic
stop—unlawfully, as it turned out, given the lack of probable
cause—law enforcement would have discovered the narcotics
and firearm under the Live Stop Policy because the car would
have been impounded and then searched for inventory
purposes.
Having lost the suppression argument, Sok proceeded
to a jury trial and was convicted of all three counts noted above.
He was sentenced to 240 months’ imprisonment and four years
of supervised release. He appeals from the judgment of his

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conviction and sentence.3
II. Discussion
On appeal, Sok argues that the Government has not
demonstrated that any impoundment of his vehicle would have
been lawful or inevitable, meaning the inevitable-discovery
doctrine does not apply and the physical evidence used against
him should have been suppressed as being unlawfully seized.
For his first argument, concerning the lawfulness of the
potential impoundment under the Live Stop Policy, he
contends the Government has not demonstrated that an
impoundment based solely on his vehicle’s expired registration
would have been reasonable as an exercise of a community-
caretaking function—an exception to the Fourth Amendment’s
warrant requirement. See United States v. Smith, 522 F.3d 305,
313–14 (3d Cir. 2008); see also South Dakota v. Opperman,
428 U.S. 364, 369 (1976) (“The authority of police to seize and
remove from the streets vehicles impeding traffic or
threatening public safety and convenience is beyond
challenge.”). For his second argument, concerning the
inevitability of the potential impoundment under the Live Stop
Policy, Sok claims that the Government has failed to
demonstrate that all of the contingencies to impoundment, such
as a tow truck arriving within the prescribed window of 30
minutes, would inevitably have occurred to result in the car
being towed and inventoried but for Mason’s illegal search.
The problem is that Sok did not raise these two
3 The District Court had jurisdiction under 18 U.S.C. § 3231.
We have jurisdiction under 28 U.S.C. § 1291 and 18 U.S.C.
§ 3742(a).

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arguments before the District Court. Instead, the only
argument he made was that the inevitable-discovery doctrine
did not apply because no impoundment under the Live Stop
Policy actually occurred. But, as Sok concedes, that sole
“argument . . . was wrong” because it “speaks to the related but
distinct independent source doctrine, not inevitable discovery.”
Reply Br. at 2. The two doctrines differ as follows:
[U]nder the independent source doctrine,
evidence that was in fact discovered lawfully,
and not as a direct or indirect result of illegal
activity, is admissible. In contrast, the inevitable
discovery doctrine, applied in Nix [v. Williams,
467 U.S. 431 (1984)], permits the introduction of
evidence that inevitably would have been
discovered through lawful means, although the
search that actually led to the discovery of the
evidence was unlawful. The independent source
and inevitable discovery doctrines thus differ in
that the former focuses on what actually
happened and the latter considers what would
have happened in the absence of the initial
search.
United States v. Herrold, 962 F.2d 1131, 1140 (3d Cir. 1992)
(emphases in original). While the fact that no impoundment
actually occurred would be relevant to an independent-source
defense raised by the Government, it is not relevant to the
Government’s inevitable-discovery defense raised here.
Yet Sok contends that he functionally made the same or
similar arguments before the District Court and can reframe
them on appeal. In this regard, we require litigants to preserve

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specific arguments for appeal, not merely issues. United States
v. Joseph, 730 F.3d 336, 341 (3d Cir. 2013) (“[R]aising an
issue in the District Court is insufficient to preserve for appeal
all arguments bearing on that issue. Instead, to preserve a
suppression argument, a party must make the same argument
in the District Court that he makes on appeal.”). In other
words, “raising an issue is not sufficient to preserve all
arguments within the issue.” Id. Determining whether an
argument raised on appeal is the same as one raised in the trial
court requires at least that “they depend on the same legal rule
or standard” and “on the same facts.” Id. at 342. And while
“[p]arties are free . . . to place greater emphasis and more fully
explain an argument on appeal than they did in the District
Court [and] may even, within the bounds of reason, reframe
their argument,” “they may not change [its] substance.” Id. at
341.
Sok simply did not raise, in any form, his two arguments
against inevitable discovery before the District Court. While
he cited the legal rule for inevitable discovery and noted some
of the steps in the Live Stop Policy’s procedure for
impoundment in his supplemental briefing, he did not argue
that the Government failed to demonstrate an impoundment
would have been lawful or inevitable. Instead, as discussed,
his trial attorney appears simply to have confused the
inevitable-discovery and independent-source doctrines. By
arguing that no impoundment under the Live Stop Policy
actually occurred, Sok’s trial counsel did not address the
Government’s inevitable-discovery defense, which relies on
the premise that an impoundment, although it did not occur,
would inevitably have occurred under the Policy. Nor did
Sok’s counsel otherwise attempt to raise the arguments he
presses here, such as through a motion for reconsideration of

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the suppression ruling.
Because Sok failed to raise before the District Court the
two suppression-related arguments he presses on appeal, we
cannot consider them under Federal Rule of Criminal
Procedure 12 unless he shows good cause for us to do so.
A. Rule 12’s “Good Cause” Standard for Untimely
Arguments
Rule 12 requires that certain “defenses, objections, and
requests must be raised by pretrial motion if the basis for the
motion is then reasonably available and the motion can be
determined without a trial on the merits[.]” Fed. R. Crim. P.
12(b)(3). Arguments related to the “suppression of evidence”
are included among the issues that must be raised before trial.
Id. 12(b)(3)(C). Rule 12 also specifies the consequences for
failing to raise an argument in a timely motion:
If a party does not meet the deadline for making
a Rule 12(b)(3) motion, the motion is untimely.
But a court may consider the defense, objection,
or request if the party shows good cause.
Fed. R. Crim. P. 12(c)(3). Under that text, Sok’s suppression-
related arguments are untimely, and we can consider them only
if he shows good cause for us to do so.
Sok counters that we should consider his untimely
arguments under Federal Rule of Criminal Procedure Rule
52(b)’s plain-error standard rather than the good-cause
standard in Rule 12. Rule 52(b) provides that “[a] plain error
that affects substantial rights may be considered even though it

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was not brought to the court’s attention.” Fed. R. Crim. P.
52(b). In other words, to determine if there is plain error, we
ask whether there was an “error” that was “plain” and “affects
[the defendant’s] substantial rights.” Id.; see United States v.
Olano, 507 U.S. 725, 732–35 (1993). Further, we do not
exercise our discretion to address such an error unless it
“seriously affect[s] the fairness, integrity or public reputation
of judicial proceedings.” Olano, 507 U.S. at 732 (internal
quotation and citation omitted).
Contrary to Sok’s position, however, we have held that
Rule 12’s good-cause standard of review trumps Rule 52(b)’s
plain-error standard for issues that must be raised before trial
under Rule 12. Rose, 538 F.3d at 182–84. Specifically, we
reasoned that Rule 12 is a narrower provision that “singles out”
the issues in Rule 12(b)(3), including suppression, and that its
standard of review thus prevails over that of the more generally
applicable Rule 52(b). Id. at 182–83; see also In re
Combustion Eng’g, Inc., 391 F.3d 190, 237 n.49 (3d Cir.
2004), as amended (Feb. 23, 2005) (noting the “well-settled
maxim that specific statutory provisions prevail over more
general provisions”).4
4 At least before the 2014 amendment to Rule 12, discussed
further below, most courts of appeals followed the approach
we took in Rose, concluding that Rule 12’s good-cause
standard applies to untimely Rule 12 arguments raised for the
first time on appeal rather than Rule 52(b)’s plain-error rule.
See Rose, 538 F.3d at 180 (describing this as the “prevailing”
rule (citation omitted)); United States v. Chavez-Valencia, 116
F.3d 127, 132–33 (5th Cir. 1997) (listing cases); United States

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Sok argues that this holding in Rose—i.e., that we
review untimely Rule 12 arguments only if there is good cause
to do so and do not review for plain error—does not survive a
2014 amendment to the text of Rule 12. We disagree. Since
v. Walker, 665 F.3d at 228 (1st Cir.) (calling it the “majority
view”).
That said, there were differing approaches to resolving
the tension between Rule 12 and Rule 52(b) for Rule 12 pretrial
issues raised for the first time on appeal. Some cases applied
Rule 52(b)’s plain-error rule, at times without even mentioning
Rule 12. See, e.g., United States v. Stevens, 487 F.3d 232, 242
(5th Cir. 2007); United States v. Buchanon, 72 F.3d 1217, 1227
(6th Cir. 1995); United States v. Moore, 104 F.3d 377, 382
(D.C. Cir. 1997). Other circuits were at times internally
inconsistent, sometimes applying Rule 12’s good-cause
standard and sometimes applying plain-error review. See, e.g.,
Chavez-Valencia, 116 F.3d at 132–33 (identifying “intra-
circuit conflicts”); United States v. Soto, 794 F.3d 635, 649
(6th Cir. 2015) (noting intra-circuit inconsistency); United
States v. Anderson, 783 F.3d 727, 740 (8th Cir. 2015) (same).
The Seventh Circuit sometimes used a mixed solution,
which first applied Rule 12’s good-cause standard and, if the
party showed good cause, then determined whether there was
plain error under Rule 52(b). See, e.g., United States v. King,
627 F.3d 641, 647 (7th Cir. 2010); United States v. Hargrove,
508 F.3d 445, 450 (7th Cir. 2007). The Seventh Circuit has
also applied a different solution altogether, requiring appellate
courts to ask whether it would have been within the trial court’s
discretion to reject a Rule 12 argument as untimely if it had
been raised in the trial court initially. See, e.g., United States
v. Acox, 595 F.3d 729, 732 (7th Cir. 2010); United States v.
Kirkland, 567 F.3d 316, 322 (7th Cir. 2009).

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the 2014 amendment, we have continued to apply the rule that
suppression arguments raised for the first time on appeal are
not considered except for good cause. See, e.g., United States
v. Scarfo, 41 F.4th 136, 169 (3d Cir. 2022), cert. denied sub
nom. Pelullo v. United States, 143 S. Ct. 1044 (2023). Yet
because we have not examined the issue at length, we do so
today.
At the time we decided Rose, Rule 12 provided the
following consequence for failing to raise a suppression issue
(or any other Rule 12(b)(3) issue) in a timely fashion:
A party waives any Rule 12(b)(3) defense,
objection, or request not raised by the deadline
the court sets under Rule 12(c) or by any
extension the court provides. For good cause,
the court may grant relief from the waiver.
Fed. R. Crim. P. 12(e) (prior to 2014 amendment) (emphases
added). The 2014 amendment to Rule 12 removed the
“waiver” language from Rule 12(e). See Fed. R. Crim. P.
12(e). Instead, the consequences for failing to raise timely one
of the issues listed in Rule 12(b)(3), for which a pretrial motion
is required, are now described in Rule 12(c)(3), as set out
above.
Sok’s argument relies on the fact that our holding in
Rose was based in part on the now-removed “waiver” language
of the former Rule 12(e). See Rose, 538 F.3d at 179–84.
Specifically, we concluded that Rule 12(e) “mean[t] what it
sa[id]” and, consequently, suppression arguments raised for the
first time on appeal are not considered merely forfeited but
“waived,” meaning they cannot be considered (absent good

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cause). Id. at 183. We reached this conclusion while noting
that the former Rule 12(e)’s use of the term “waiver” sat
uncomfortably with the distinction between forfeiture and
waiver drawn by the U.S. Supreme Court in Olano, where the
Court clarified that “waiver” refers to the “intentional
relinquishment or abandonment of a known right,” whereas
“forfeiture” is the “failure to make the timely assertion of a
right . . . .” 507 U.S. at 733 (internal quotation omitted); see
Rose, 538 F.3d at 183; see also United States v. Dowdell, 70
F.4th 134, 140 (3d Cir. 2023) (observing the same distinction
as Olano).5
While the 2014 amendment to Rule 12 removed the
“waiver” language—and thus rescinds the portion of our
reasoning in Rose dependent on that language—it did not
change the standard of review for Rule 12(b)(3) arguments
raised for the first time on appeal. Those arguments still must
be raised by the pretrial deadline; if not, they are “untimely.”
Fed. R. Crim. P. 12(c)(3). And we still can review “untimely”
5 Under Olano’s distinction between the two terms, the
inadvertent failure to raise a timely Rule 12(b)(3) argument
would be treated as a forfeiture rather than a waiver. See Rose,
538 F.3d at 183 (“Per [Olano], failure to comply with Rule 12
could be seen as more akin to a forfeiture . . . .”). As such, it
would be subject to plain-error review. See id.; Fed. R. Crim.
P. 52(b); see also Olano, 507 U.S. at 733 (“Mere forfeiture, as
opposed to waiver, does not extinguish an ‘error’ under Rule
52(b).”). Yet, despite Rule 12(e)’s apparent misuse of the term
“waiver,” we concluded that it nonetheless meant what it said
and, as a result, we would not review untimely Rule 12
arguments (not even for plain error) unless there was good
cause to do so. Rose, 538 F.3d at 183–84.

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Rule 12(b)(3) arguments only if a party shows “good cause”
for us to do so. Id. Nothing in the text of Rule 12 after the
2014 amendment supplants its good-cause standard of review
in favor of Rule 52(b)’s plain-error standard. This is further
supported by the Advisory Committee note accompanying the
2014 amendment, which explains the reason for the removal of
the “waiver” terminology:
New paragraph (c)(3) governs the review of
untimely claims, previously addressed in Rule
12(e). Rule 12(e) provided that a party “waives”
a defense not raised within the time set under
Rule 12(c). Although the term waiver in the
context of a criminal case ordinarily refers to the
intentional relinquishment of a known right,
Rule 12(e) has never required any determination
that a party who failed to make a timely motion
intended to relinquish a defense, objection, or
request that was not raised in a timely fashion.
Accordingly, to avoid possible confusion the
Committee decided not to employ the term
“waiver” in new paragraph (c)(3).
Fed. R. Crim. P. 12, Advisory Committee Note to 2014
Amendment.6 This amendment, the Advisory Committee
emphasizes, did not change the standard of review for untimely
6 While not binding on us, the Advisory Committee’s notes are
“of weight” in our interpretation of the Federal Rules. Moore
v. Walton, 96 F.4th 616, 624 (3d Cir. 2024) (quoting In re Nat.
Football League Players Concussion Inj. Litig., 775 F.3d 570,
577 n.6 (3d Cir. 2014)).

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arguments:
New paragraph 12(c)(3) retains the existing
standard for untimely claims. The party seeking
relief must show “good cause” for failure to
raise a claim by the deadline, a flexible standard
that requires consideration of all interests in the
particular case.
Id. In other words, Rule 12 continues to mean what it says and
“provides only one circumstance in which an untimely motion
can be considered—when the movant ‘shows good cause.’”
United States v. Bowline, 917 F.3d 1227, 1230 (10th Cir. 2019)
(quoting Fed. R. Crim. P. 12(c)(3)).7 Accordingly, Sok must
meet that measure for us to consider his untimely suppression
7 We note that some courts of appeals have changed their
position in light of the 2014 amendment and now use plain-
error review for Rule 12 arguments raised for the first time on
appeal. See, e.g., United States v. Vasquez, 899 F.3d 363, 372–
73 (5th Cir. 2018), as revised (Aug. 24, 2018); Soto, 794 F.3d
at 648–55 (6th Cir); United States v. Sperrazza, 804 F.3d 1113,
1118–19 (11th Cir. 2015); see also 1A Charles Alan Wright &
Arthur R. Miller, Federal Practice and Procedure § 194 &
nn.22–23 (5th ed. West) (“Some appellate courts now conclude
that untimely motions should be subject to plain error review
in the absence of evidence that the defendant intentionally
relinquished the claim, either because they found the change in
language in the 2014 amendments significant, or because the
approach was dictated by circuit precedent.”). Nonetheless, we
stick with the text of Rule 12, which states that “good cause”
is the standard of review for untimely Rule 12(b)(3) arguments.

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arguments.
B. Good Cause
We have not rigidly demarcated what may qualify as
“good cause” to excuse the untimeliness of a Rule 12 argument
raised for the first time on appeal.8 The Supreme Court has
indicated that, as a general matter, a showing of both cause and
prejudice is necessary on direct appeal and collateral review.
8 If a district court makes a “good cause” determination for an
untimely Rule 12 argument in the first instance, we review for
abuse of discretion. United States v. Desu, 23 F.4th 224, 232
(3d Cir. 2022); see also Davis v. United States, 411 U.S. 233,
245 (1973). The District Court made no such determination
here because Sok did not attempt to make his two suppression-
related arguments before it.
We have previously held that we can determine “cause”
for the first time on appeal under Rule 12, so long as there is
no need to remand the case for an evidentiary hearing. See
Rose, 538 F.3d at 184. We continue to follow that approach,
although we recognize that other courts have reached different
conclusions. See, e.g., Soto, 794 F.3d at 655 (6th Cir.)
(applying plain-error rather than good-cause standard in part
because the “good-cause standard may be difficult to apply on
appeal if the issue was not first raised at the district court
because review for good cause often requires developing and
analyzing facts”); Acox, 595 F.3d at 732 (7th Cir.)
(determining that appellate courts cannot determine “good
cause” under Rule 12 on first impression but may inquire
whether, if a motion for relief had been made and denied by
the district court, it would have abused its discretion in doing
so).

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See Shotwell Mfg. Co. v. United States, 371 U.S. 341, 363
(1963); Davis v. United States, 411 U.S. 233, 242–44 (1973);
Wainwright v. Sykes, 433 U.S. 72, 84 (1977); see also Bowline,
917 F.3d at 1232–34 (discussing Davis and Sykes and requiring
both cause and prejudice); see also United States v. Mayer, 63
F.4th 680, 684 (8th Cir. 2023) (requiring cause and prejudice);
United States v. Santana-Dones, 920 F.3d 70, 81 (1st Cir.
2019) (same).
There is a lack of consensus, however, concerning how
flexible the standard should be. One approach treats it as
broadly flexible and fact-dependent. See, e.g., United States v.
Walden, 625 F.3d 961, 965 (6th Cir. 2010) (“Good cause is a
flexible standard heavily dependent on the facts of the
particular case as found and weighed by the district court in its
equitable discretion.”); see also Fed. R. Crim. P. 12, Advisory
Committee Note to 2014 Amendment (“The party seeking
relief must show ‘good cause’ for failure to raise a claim by the
deadline, a flexible standard that requires consideration of all
interests in the particular case.”); 1A Charles Alan Wright &
Arthur R. Miller, Federal Practice and Procedure § 194 &
n.31 (5th ed. West). Another approach construes the exception
narrowly. United States v. Burke, 633 F.3d 984, 988 (10th Cir.
2011) (“We rarely, however, grant relief under the good-cause
exception.”); United States v. Santos Batista, 239 F.3d 16, 19
(1st Cir. 2001) (describing “good cause” as “single narrow
exception to the waiver rule”); see also Wright & Miller,
supra, § 194 & n.32.
We think that “good cause” under Rule 12 is a flexible
standard that will necessarily depend on the circumstances of
a particular case. Such treatment accords with the Advisory
Committee’s advice and the fact that we grant district courts

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discretion in determining whether there is good cause to excuse
untimely Rule 12 arguments. See Fed. R. Crim. P. 12,
Advisory Committee Note to 2014 Amendment; United States
v. Desu, 23 F.4th 224, 232 (3d Cir. 2022).
To direct the application of this flexible standard in our
case, there are some guideposts already in place. Good cause
may be shown where the information supporting the claim
arose too late to file a timely Rule 12 motion. See United States
v. Fattah, 858 F.3d 801, 808 (3d Cir. 2017), as amended (June
12, 2017) (“late-breaking” evidence supported good cause
determination); cf. United States v. Pitt, 193 F.3d 751, 760 (3d
Cir. 1999), as amended (Oct. 15, 1999), and abrogated on
other grounds by Honeycutt v. United States, 581 U.S. 443
(2017) (concluding there was no good cause shown where
defendant was “always aware of the facts upon which he”
based a Rule 12 argument made for the first time on appeal).
Mere inadvertence of counsel, however, will typically not be
enough to show good cause for raising a Rule 12(b)(3)
argument for the first time on appeal. See, e.g., United States
v. Andres, 960 F.3d 1310, 1316 (11th Cir. 2020).9 And the
9 Sok does not make any argument that his trial counsel was
constitutionally ineffective, so we do not address whether
ineffective assistance of counsel may constitute “good cause”
to satisfy Rule 12. We do note, however, that ineffective-
assistance-of-counsel claims should generally be raised
collaterally. See, e.g., United States v. Jake, 281 F.3d 123, 132
n.7 (3d Cir. 2002); see also United States v. Taylor, 792 F.2d
1019, 1025 (11th Cir. 1986) (“We are sympathetic to [the
defendant’s] argument that a defendant should not be penalized
for the inadvertence of his or her counsel but are at a loss to see

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failure to offer “any colorable explanation” for an untimely
Rule 12 argument plainly does not suffice to show good cause.
Rose, 538 F.3d at 184.
As discussed, Sok’s only justification for his failure to
make his suppression-related arguments before the District
Court, despite having the opportunity to do so, was his
counsel’s apparent confusion about the applicable law—i.e.,
the difference between the inevitable-discovery and
independent-source doctrines. By arguing only that no
impoundment actually occurred, his counsel inadvertently
failed to address the Government’s inevitable-discovery
defense. Instead, his counsel’s argument went to the
independent-source rule, which was not and is not at issue.
This mistake is not sufficient to demonstrate good cause.
Moreover, Sok does not contend that the facts underlying his
arguments raised for the first time on appeal were not available
to him to make a timely argument before the District Court.
Nor does he make any argument that the law at issue was not
well-established at the time of his counsel’s misunderstanding.
See Herrold, 962 F.2d at 1140 (describing the difference
between the inevitable-discovery and independent-source
doctrines).
Sok encourages us to define “good cause” as
how we can hold that a district court must entertain a
suppression motion untimely filed due to inadvertence of
counsel without completely eviscerating Rule 12(b)(3).”). But
see United States v. Johnson, 47 F.4th 535, 540 (7th Cir. 2022),
cert. denied, 143 S. Ct. 813 (2023) (“A claim of ineffective
assistance of counsel might constitute good cause based on a
fully developed record.”).

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contemplating not only justifications going to the timeliness of
Rule 12(b)(3) arguments—e.g., claiming the facts underlying
a Rule 12 claim raised for the first time on appeal were not
previously available—but also a broader range of
considerations, including exceptional or extraordinary
circumstances. By this, he points out an exception to forfeiture
we have typically applied in civil cases10: while we do not
reach waived arguments, we can reach forfeited issues if there
are extraordinary or exceptional circumstances counseling us
to do so. See Dowdell, 70 F.4th at 140; Barna v. Bd. of Sch.
Dirs. of Panther Valley Sch. Dist., 877 F.3d 136, 147 (3d Cir.
2017).11
Even assuming that the good-cause standard under Rule
10 We have also looked to the extraordinary-circumstances
exception to forfeiture under direct criminal and collateral
review where a defendant fails to raise an issue in an opening
brief. See United States v. Andrews, 681 F.3d 509, 532 (3d Cir.
2012) (direct); United States v. Albertson, 645 F.3d 191, 195
(3d Cir. 2011) (direct); United States v. Pelullo, 399 F.3d 197,
222 (3d Cir. 2005), as amended (Mar. 8, 2005) (collateral).
11 We have previously stated that we can review untimely
appellate arguments—i.e., arguments raised for the first time
on appeal or raised on appeal only after an opening appellate
brief—if there are extraordinary circumstances to do so. See,
e.g., Brenner v. Loc. 514, United Bhd. of Carpenters & Joiners
of Am., 927 F.2d 1283, 1298 (3d Cir. 1991); In re Mystic Tank
Lines Corp., 544 F.3d 524, 528 (3d Cir. 2008); Andrews, 681
F.3d at 532. Yet we have often described these scenarios in
terms of “waiver.” See Brenner, 927 F.2d at 1298 (“It is well
established that failure to raise an issue in the district court

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12(c)(3) incorporates some or all of the considerations we have
applied under our exceptional-circumstances jurisprudence,
Sok has not demonstrated exceptional circumstances here. To
determine whether they exist, we typically consider any excuse
for the untimeliness, the extent to which considering the issue
would prejudice the opposing party, and whether our failure to
consider it would result in a “miscarriage of justice or
undermine confidence in the judicial system.” United States v.
Andrews, 681 F.3d 509, 532 (3d Cir. 2012) (quoting United
States v. Albertson, 645 F.3d 191, 195 (3d Cir. 2011) (adopting
these principles)). We have also looked to whether the “public
interest requires that the new issue be heard on appeal,” United
States v. Petersen, 622 F.3d 196, 202 n.4 (3d Cir. 2010)
(citation omitted), and whether it involves a pure question of
law, Barna, 877 F.3d at 147 (“Although our narrow
exceptional circumstances rule applies to all forfeited issues,
we have been slightly less reluctant to bar consideration of a
constitutes a waiver of the argument.” (emphasis added));
Pelullo, 399 F.3d at 222 (“It is well settled that an appellant’s
failure to identify or argue an issue in his opening brief
constitutes waiver of that issue on appeal.” (emphasis added)).
But this usage of “waiver” is inconsistent with the waiver-
forfeiture distinction drawn by the Supreme Court in Olano
and emphasized by our Court in Dowdell. See Olano, 507 U.S.
at 733; Dowdell, 70 F.4th at 140 (“Although we cannot reach
waived arguments, appellate courts may resurrect forfeited
arguments in extraordinary circumstances.” (internal
quotations and citation omitted)). Instead, absent any
intentional abandonment, we would now refer to such untimely
or unpreserved arguments as being forfeited. See Olano, 507
U.S. at 733.

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forfeited pure question of law.”).
Again, Sok’s only justification for failing to raise his
arguments against inevitable discovery before the District
Court is his counsel’s inadvertence. Moreover, reviewing his
forfeited arguments would prejudice the Government.
Because it was not put on notice of Sok’s arguments against its
theory of inevitable discovery before the District Court, the
Government had no opportunity to develop the record with
evidence to rebut them. See Rose, 538 F.3d at 182. Nor does
Sok point to any countervailing public interest.12
Additionally, refusing to address Sok’s arguments will
not result in a miscarriage of justice. We have likened the
miscarriage-of-justice factor to plain-error review. See
Albertson, 645 F.3d at 196; Andrews, 681 F.3d at 532. Even
if, for the sake of argument, we apply that standard of review
here, Sok does not succeed because, at the least, he has not
shown that any error here was “plain.” See Olano, 507 U.S. at
734. He points to no governing caselaw resolving the issues
presented: whether the Government has adequately
demonstrated that any impoundment of his car for its invalid
12 To the extent Sok argues that an untimely Rule 12 argument
presenting a purely legal issue—without more—presents
exceptional circumstances, we disagree. Such a broad-based
exception would swallow the Rule 12 good-cause standard.
See Rose, 538 F.3d at 183 n.8 (“[W]e think it unwise to excuse
a defendant from compliance with Rule 12 even where the
court of appeals thinks the record is sufficiently developed. To
do so would ignore the specific language of Rule 12, something
we do not consider ourselves at liberty to do.”).

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registration would have been lawful or inevitable.
On the potential impoundment’s legality, Sok appeals
only to the broad principles underlying the community-
caretaking exception to the Fourth Amendment’s warrant
requirement. See, e.g., Opperman, 428 U.S. at 368–70; Smith,
522 F.3d at 313–15. “Th[e] community caretaking
doctrine . . . is an exception to the warrant requirement of the
Fourth Amendment and allows police with a non-law
enforcement purpose to seize or search a person or property ‘in
order to ensure the safety of the public and/or the individual,
regardless of any suspected criminal activity.’” Vargas v. City
of Philadelphia, 783 F.3d 962, 971 (3d Cir. 2015) (quoting
United States v. King, 990 F.2d 1552, 1560 (10th Cir. 1993)).
He argues that the Government has failed to show that any
impoundment under the Live Stop Policy would have served
the public safety, noting that it has even conceded that the
“vehicle could have been locked and left at the location of the
traffic stop while Sok was taken into custody . . . .” App. 209.
On this basis, he argues that his vehicle’s mere lack of
registration, without more, is insufficient to allow for
impoundment under the community-caretaking exception. Yet
he points to no governing caselaw that clearly supports his
view. The same goes for his argument that the Government
failed to show that any impoundment and subsequent inventory
search would inevitably have occurred.
There being no plain error, we fail to see how a
miscarriage of justice could result from refusing to reach the

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merits of Sok’s arguments.13 For these reasons, there are no
13 While any error was not “plain,” we nonetheless express
some concern with the Government’s view of the scope of the
inevitable-discovery doctrine in this case. It is its burden to
demonstrate, by a preponderance of the evidence, that the
evidence that the defendant seeks to suppress would have been
inevitably discovered through lawful means. United States v.
Vasquez De Reyes, 149 F.3d 192, 195 (3d Cir. 1998); see Nix,
467 U.S. at 444. The only justification the Government
provides for the legality of impounding Sok’s vehicle is its lack
of valid registration. It is unclear if this, without more, passes
muster under the reasonable community-caretaking exception
to justify the warrantless impoundment of Sok’s vehicle. See
Opperman, 428 U.S. at 369; Smith, 522 F.3d at 313–15. While
it is true that, under state law, a car with an expired registration
cannot be driven, 75 Pa. C.S. §§ 1301, 6309.2(a)(2), the
Government has not shown that Sok’s car would have needed
to be moved for any reason. Instead, as discussed, it conceded
that the vehicle could have been left where it was. Without
more, invalid vehicle registration might not present a sufficient
public-safety interest to justify warrantless impoundment. See,
e.g., United States v. Cervantes, 703 F.3d 1135, 1141 (9th Cir.
2012) (concluding impoundment of vehicle was not justified
by community-caretaking exception where there was no
evidence the vehicle “was parked illegally, posed a safety
hazard, or was vulnerable to vandalism or theft”); United
States v. Chavez, 985 F.3d 1234, 1243–45 (10th Cir. 2021)
(refusing to apply the community-caretaking exception to the
seizure of an unattended firearm from a vehicle where the
vehicle was lawfully parked and there was little risk someone
would take the firearm). We also note that the Philadelphia

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exceptional circumstances for reaching Sok’s untimely Rule 12
arguments (again, assuming Rule 12(c)(3)’s good-cause
standard incorporates our exceptional-circumstances
jurisprudence).
* * *
We hold that Rule 12(c)(3)’s good-cause standard
applies to Sok’s suppression-related arguments raised for the
first time on appeal rather than plain-error review under Rule
52(b). Because Sok has not demonstrated good cause for his
failure to raise these arguments before the District Court, we
cannot consider their merits. Given that his untimely
arguments are the only grounds for his appeal, we affirm the
judgment of the District Court.
Police Department has since amended the Live Stop Policy in
a manner that incorporates a public-interest requirement. See
supra note 1. Nonetheless, while we have concerns with the
Government’s expansive view of the community-caretaking
exception in this case, we do not reach the merits for the
reasons discussed.

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