When the Supreme Court rules in King v. Burwell, the new Obamacarechallenge, its judges won't be the first to grapple with whether the health law's subsidies on the federal marketplace are legal.

Since early 2014, five separate courts have issued rulings on the issue in three separate health law challenges. Three courts have ruled in the Affordable Care Act's favor; two have ruled against the subsidies.

Even for those following the case closely, it can be difficult to keep track of all those decisions. That's why my colleague Anand Katakam and I put together this timeline of all the court decisions:

Here's a bit more on the three lawsuits:

Pruitt v. Burwell

This challenge, filed in late 2012 by Oklahoma Attorney General Scott Pruitt, was the first lawsuit to argue that Obamacare's subsidies on the federal marketplace were illegal. It's important because it marked the first time a plaintiff actually got on board with a legal argument that had been circulating in conservative legal circles for about a year. Even though Pruitt was filed first, it has moved the slowest through the courts. It was only this past fall that a district court ruled in Oklahoma's favor, finding the Obama administration's decision to administer subsidies on the federal marketplace to be " arbitrary, capricious, an abuse of discretion or otherwise not in accordance with law."

Important documents:

Halbig v. Burwell

Challengers filed in court in May 2013, about six months after the Pruitt case. The Competitive Enterprise Institute is funding this case, as well as King v. Burwell. Halbig is different from Pruitt because it includes private citizens and businesses as its plaintiffs. This was strategic on the part of the law's challengers: they wanted to give courts as many different arguments as possible to choose from. In Halbig, a district court initially ruled in the government's favor — but the Court of Appeals for the District of Columbia reversed that decision in July. This is the other ruling against the law, alongside Pruitt.

Important documents:

King v. Burwell

This is the lawsuit that the Supreme Court decided to hear in November. Like Halbig, it also includes private citizens and business owners as challengers to the law. Both courts that have heard the King argument have ruled in the Obama administration's favor, finding the health law's subsidies to be legal.

Important documents

There is a fourth challenge to the health law's subsidies, Indiana v. IRS. This challenge includes the state of Indiana as well as dozens of Indiana school districts, also arguing against the health law's subisidies. We did not, however, include it in our timeline as there have not yet been any court decisions on the case.

This post is indebted to Michael Cannon, who has aggregated these documents (as well as many others) in his Forbes guide to the health law challenges.