On Monday morning, the Supreme Court announced that it will consider the constitutionality of the Obama health care reform law this term, guaranteeing a decision on the landmark legislation by the end of June, right in the middle of the 2012 election campaign. The administration seems fairly confident that the court won’t, in fact, overturn the law. It has asked for an expedited review of the legal challenges, and, like the law’s opponents, it has pressed the court to settle the matter as soon as possible so states can move forward with implementing the law.

“We know the Affordable Care Act is constitutional and are confident the Supreme Court will agree,” White House communications director Dan Pfeiffer said in a statement Monday morning. The administration has good reason to be optimistic—and if the law is eventually upheld, the Obama team might owe a thank you to a surprising group of people: pot smokers. Here’s why.

In both the DC Circuit and the 6th Circuit, the two appellate courts that have upheld the health care law, judges relied heavily on a 2005 Supreme Court ruling in Gonzalez v. Raich—a medical marijuana case. That case involved a California woman named Diane Monson who’d been growing marijuana in her backyard for medicinal reasons. (Monson was joined in the case by Angel Raich, a woman who’d also had her medicinal marijuana seized by federal agents.) The DEA swooped in one day and destroyed her plants, even though medical marijuana use in California is legal under state law. The high court found that the Commerce Clause gave Congress wide authority to regulate interstate commerce, even when that commerce takes place mostly in someone’s backyard.

Monson had claimed the DEA’s action was unconstitutional and a violation of the Commerce Clause because federal agents were moving to prohibit noncommercial, intrastate cultivation of a plant intended for personal consumption. The pot wasn’t crossing state lines—it wasn’t even being sold at all. That, the plaintiffs believed, made the weed beyond the reach of the feds.