Marijuana and its struggle to become legalized was the subject of John Oliver’s Last Week Tonight on Sunday, as he showed the drug – which he dubbed “catnip for people” – has come up against federal blockades despite being legal on a state level.

He started with reminding viewers that on election night there was a silver lining for anti-Trump voters who supported the legalization of weed.

“One small bright spot on election night was pro-marijuana referenda passing in eight states,” said Oliver. “It’s a little weird that celebrations happened on the same night Trump was elected. It’s like celebrating your baseball team winning on the deck of the sinking Titanic.”

He added that 44 states have some form of medical marijuana law and eight have recreational use. “That is good news,” he said. “The war on drugs was futile, expensive and imposed overly harsh penalties especially on African Americans, which police data suggests are more than four times more likely to be arrested for marijuana possession.”

But despite progress on a state level, Oliver reminded his audience that because of the difference in federal law – where the drug is still illegal – even those who acquire the drug legally could be in trouble.

“If you have marijuana right now, even if you are acting completely legally according to your state, you may still be in serious jeopardy,” he said. “You could lose your home, job or possessions. This story is genuinely worth worrying about.”

“Naturally, it was Richard Nixon, the Mozart of racially motivated lawmaking, who targeted it in his war on drugs,” he said.

Oliver then played a recording of Nixon talking about how he thought there was a Jewish conspiracy to legalize the drug in the 70s. The Controlled Substances Act in 1970, which is still in effect and means marijuana is classed as a schedule one drug, the highest possible classification, alongside heroin.

Oliver explained that federal law is now clashing with state laws, as states – such as California – seek to make the drug legal. One of the knock-on effects of this is that legal medical marijuana companies struggle to get bank accounts because on a federal level they are still illegal.

“That is a shitty way to be forced to do business,” he added. “On a suspicious scale, cash-stuffed envelopes rank somewhere between unfurled hundreds dusted in white powder and a wad of damp ones containing a single pubic hair.”

Oliver then sketched out the impact of the difference between federal and state law. It means companies can’t deduct certain expenses so they have far higher tax bills, and users of medical marijuana can be fired if they fail drugs tests – even in states where the drug is legal, and children can be taken from parents who use medical marijuana.

Veterans and their use of the drug to help with PTSD was also discussed as Oliver showed footage of a Vietnam veteran in Kentucky who claimed that the drug was the only way he could overcome nightmares and flashbacks.

He said: “So for all the talk you hear of marijuana being a gateway drug, for him that gateway led to peaceful sleep, rigorous exercise and community service.”

Again the difference between state and federal law came up as Oliver said that in Kentucky, where the veteran was from it would be illegal for a doctor from the Veterans Administration to write him a prescription because it’s a federal entity.

Oliver then spoke about how under Barack Obama, the federal approach to marijuana was more lenient, but with Jeff Sessions as attorney general things could soon become more draconian.

“If an 83-year-old Republican from Alaska has come around on this issue, then it’s probably time for our laws to catch up,” said Oliver speaking about the cannabis caucus.