A federal appeals court Tuesday heard arguments in a key case that could help determine the fate of the Affordable Care Act. Twenty-one Democratic attorneys general and the Democrat-led House of Representatives are challenging a decision by a Texas judge last December that ruled the “individual mandate” provision of Obamacare to be unconstitutional, effectively invalidating the act. Eighteen Republican state attorneys general and two Republican governors brought the original suit. Earlier this year, the Trump administration backed the ruling and said the ACA should be dismantled. The 5th Circuit Appeals Court’s ruling will likely be challenged be the opposing side, setting the case up for a Supreme Court battle.