Key legal question
Whether the final social security assessment order was null and therefore not a valid title for definitive debt enforcement.
Extracted holding
The order was not void; any defects were at most challengeable substantive errors, not an obvious and grave nullity defect.
Extracted reasoning
Nullity requires a particularly serious, obvious or easily recognizable defect without serious risk to legal certainty. The alleged error concerned substantive liability and was not apparent from the order itself.