One question bound to come up during Tuesday’s oral arguments in the legal challenge to Obamacare is whether the U.S. House of Representatives and 16 states can defend the law’s constitutionality when the federal government will not.

The parties’ arguments about standing have been streaming into the case because the U.S. Court of Appeals for the Fifth Circuit late last month ordered supplemental briefing and asked lawyers to address at oral argument how new case law impacts the interventions by the House and intervenor states. The Fifth Circuit also asked whether there’s still a live case or controversy to decide on appeal.