A Republican Congress member just admitted to breaking federal law.

At a marijuana conference on Tuesday, US Rep. Dana Rohrabacher, a Republican from California, admitted he tried medical marijuana to try to alleviate arthritis pain from a lifetime of surfing.

"I haven’t been able to go surfing for a year and a half, and I've been in severe pain," he said. "And you know what? I tried [a marijuana-infused topical preparation] about two weeks ago, and it's the first time … in a year and a half that I had a decent night's sleep, because the arthritis pain was gone."

This is technically illegal under federal law. Although California allows medical pot, the federal government still considers it a controlled substance with no medical value. So Rohrabacher broke federal law.

He alluded to this, joking, "Now, don't tell anybody I broke the law. They'll bust down my door."

Of course, Rohrabacher isn't alone in using marijuana to effectively treat his pain, with nearly half of states now allowing medical pot. The best review of the research to date on medical marijuana, published in the Journal of the American Medical Association, looked at 79 studies that tested cannabis's medicinal effectiveness among nearly 6,500 patients. It found solid evidence for medical cannabis to treat pain and muscle spasms.

But it's a rare event for a sitting federal lawmaker to admit he's used pot. Politicians — including Bill Clinton and President Barack Obama — typically describe it as a youthful transgression, and say they regret it. (Clinton even infamously said he didn't inhale.)

Still, it's something that researchers are taking more and more seriously, particularly in light of the opioid painkiller and heroin epidemic. A growing body of research suggests that making medical marijuana available to patients could help reduce opioid overdose deaths, since pot doesn't lead to deadly overdose but can offer the same pain relief for some patients.

At the very least, it worked for Rohrabacher. And that's going to make it just a little bit harder for the rest of Congress and the federal government to continue denying that marijuana really does have medical value for at least some people.