Lawyers for the Obama administration have been facing tough questions from an appellate court in Georgia regarding the controversial healthcare overhaul.
Attorneys general from 26 states, a coalition of small businesses, and private individuals brought the lawsuit challenging the law.
"There is nothing in the Constitution that authorizes Congress to pass a law that forces Americans to go out and buy a product. And if this law is upheld, there are potentially no limits to congressional power," Texas Attorney General Greg Abbott said.
On Wednesday, a three-judge panel for the 11th Circuit Court of Appeals in Atlanta seemed to share that sentiment, appearing uncomfortable with the mandate that all Americans carry health insurance or face penalties.
One judge questioned whether there would be any limits on congressional power should the individual mandate be upheld.
Another appeared skeptical about the government's claim that the mandate is critical to covering the uninsured.
Advocates for the law say healthcare is a unique entity.
"The court is going to find that healthcare insurance is very different than any other product. Everybody needs healthcare - you need it when you're born," said Ron Pollack, founding executive director of Families USA.
Lawyers for the Obama administration argue Congress has the right to regulate what uninsured Americans must buy since they shift $43 billion each year in medical costs to other taxpayers.
Outside the courthouse, a group of protestors disagreed with that idea.
"I don't want them to force me to buy a Chevrolet or peaches or healthcare or anything," demonstrator Jerry Shearin said.
Both sides expect a decision in the next several months but say the case will still likely go all the way to the U.S. Supreme Court.
They're expecting the final decision to be handed down a year from now.