Recreational marijuana use became legal in Canada this week, allowing adults to freely buy and consume cannabis. But admitting to using it could still get a Canadian traveler banned from the United States for life.

That’s because the U.S. government continues to treat marijuana as a Schedule 1 drug — the classification reserved for the most dangerous drugs, like heroin. On Wednesday, when our northern neighbor opened the door to recreational cannabis sales, U.S. Customs and Border Protection reiterated that it would not adjust its policies in response to Canada’s decision to liberalize its drug laws.

Instead, the agency will continue its stringent enforcement of the Immigration and Nationality Act, which bars travelers from entering the country if they admit to working in the marijuana industry, investing in a marijuana business or just having used marijuana. Even one lawfully consumed pot brownie could get a Canadian traveler blocked at the border — potentially forever.

Pretty crazy, eh?

This is just another example of how the federal government’s failure to acknowledge the shifting politics and public opinion on marijuana is creating an illogical morass of conflicting policies.

We’ve already seen this play out in the U.S., where eight states have made it legal under their laws to use marijuana recreationally and 30 have allowed the medicinal use of marijuana — even though federal law still prohibits cannabis cultivation, sale and use. Atty. Gen. Jeff Sessions rescinded the Obama administration’s largely hands-off policy toward pot operations that complied with state laws, leaving it to the U.S. attorneys in each state to determine which ones to prosecute.

Meanwhile, banks won’t serve pot companies for fear of being penalized. As a result, those companies are forced to do business and pay taxes in cash, which is hard to track and makes them targets for robberies. That’s bad policy — not only is it dangerous, it encourages tax evasion. Yet federal lawmakers have yet to fix the conflict.

Now the federal government is continuing the same head-in-the-sand approach to border enforcement.

The U.S. has already been blocking Canadians who admit to having used marijuana or working in that country’s existing, legal medical marijuana industry. In theory, the law helps border agents identify and exclude drug traffickers and addicts. But the policy has already swept up many Canadians who are neither addicts nor dealers but nevertheless get blocked from traveling to the U.S. to see the sights, do business or visit family.

One 57-year-old construction worker from British Columbia told The Times he was banned for life after he made the mistake of telling agents the truth when they asked if he had smoked pot before he got his official medical marijuana license.

Customs and Border Protection officials said last month that agents were not planning to interrogate every Canadian traveler about marijuana use. But border agents can pull travelers aside at random for additional screening, or when a traveler raises suspicion. Agents have broad discretion to ask questions of people seeking entry to the U.S., and they retain the authority to turn away noncitizens who admit to having used a controlled substance, ever.

This puts Canadian pot users in an impossible situation. If they admit to using a product that is legal in their country, they could be banned from coming into the U.S. If they lie about using marijuana and get caught, they also face a travel ban. Excluded travelers can seek a waiver from a lifetime ban, but it costs about $600 to apply, plus legal fees.

Even more confounding is that a traveler could visit, say, Seattle or San Francisco — two cities where cannabis use is allowed under state law — and legally smoke marijuana, then return to his home country. If on his next trip to the U.S. he honestly answers a border agent’s inquiry on marijuana use, he could be banned for life. In other words, travelers could be blocked because of something they’d done legally in this country. That’s ludicrous.

It makes no sense to turn away Canadian tourists, who collectively spend nearly $20 billion a year in the U.S., rather than update the nation’s outdated drug laws. Congress needs to revisit the federal prohibition and respect states and countries that want to legalize, regulate and tax marijuana.

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