Whether the Court of Administrative and Public Law had to recuse itself in corpore due to appearance of bias
Yes. Because the appellant is himself a cantonal judge and regularly has professional contacts with the judges of that court, objective appearances could create doubts of partiality.
Recusal is exceptional and requires serious grounds, but objective appearances matter under the constitutional and Convention guarantee of an impartial tribunal. The professional relationship between the appellant and the judges of the chamber justified the appearance of bias.