If you live in California, you may have celebrated the legalization of marijuana last November. But on an episode of Last Week Tonight aired Sunday, John Oliver explained that thanks to conflicts between federal and state laws, even results like the one in California can lead to confusing results where people inadvertently break the law.

Marijuana remains a Schedule 1 drug at the federal level and has been classified as such ever since President Richard Nixon brought in the Controlled Substances Act in 1970. It’s classed the same as heroin and higher than cocaine. Although states have started to pass laws legalizing the drug, this conflict has led to some frustrating situations.

Take Brandon Coates. Paralyzed from a car accident when he was a teenager, Coates had a prescription to use medical marijuana. He was fired from his job at the Dish Network when he failed a drugs test.

“It was devastating,” he told CNBC. “I was under the impression that we had passed a law, and we had made it legal.”

Unfortunately, Coates could not turn to the Americans With Disabilities Act to fight against the decision, as the act is a federal law and does not cover medicinal marijuana.

“That’s like driving exactly the speed limit and getting pulled over by a cop, who tells you ‘Sorry, the federal speed limit is three, and the legal age to drive is 62, and also you have to be drunk. Surprise!’,” Oliver said.

Businesses taking advantage of California’s new-found legalization also face hurdles. Banks, regulated by federal law, cannot help businesses that are running afoul of federal law even if the business’s state has legalized marijuana. However, these businesses still need to pay federal tax, leading to the absurd situation of stores keeping all their earnings in cash, separating out federal tax ready to pay later.

The Obama administration issued temporary guidelines toward the end of its time in office, loosening restrictions around federal rules. This is likely to come under threat from Jeff Sessions, the new attorney general, who takes a much less favorable approach to the issue.

“Good people don’t smoke marijuana,” Sessions said in a recorded speech.

But there are signs that circumstances could change at the federal level. For starters, there is now a cannabis caucus, which enjoys bipartisan support and whose leader is a Republican from Alaska.

Oliver also stressed the need for people to start campaigning now, as reforming federal law could be a slow process. If people don’t act, the legal limbo could remain in place.

Last Week Tonight airs Sundays on HBO.

Photos via Last Week Tonight/YouTube