Like many Canadians, Prime Minister Justin Trudeau has tried marijuana. He even smoked a doobie after becoming an MP. When he made that admission five years ago, he set tongues wagging. But his revelation was hardly scandalous. It actually made him relatable. For once, he came across as just another working stiff trying to unwind at home.

“We had a few good friends over for a dinner party, our kids were at their grandmother’s for the night, and one of our friends lit a joint and passed it around. I had a puff,” Trudeau told The Huffington Post Canada in 2013. He went on to explain that he’d smoked dope a handful of times, but it’s never really been his thing.

These days, the Trudeau government is preparing to legalize recreational cannabis, sparking a dubious debate about what workers should be allowed to do when they’re off the clock. Major employers in federally regulated industries, including airlines, telecoms and transportation companies, are urging Ottawa to create new drug-testing rules for some employees. Air Canada, Bell Canada, Telus, Canadian National Railway, Canadian Pacific Railway, Canada Post and the CBC are among the companies pushing for this change.

These companies seem to think we Canadians are so lacking in self-control that we’ll start toking en masse at work once pot is legal. So naturally – despite the fact that they abhor intrusive regulation – they want Ottawa’s help to keep the rank and file in check.

The hypocrisy is maddening. Mandatory drug testing is a clear human rights violation. Courts and human rights commissions across the country have already set a high bar for allowing companies to test workers in safety-sensitive jobs for drugs and alcohol.

They’ve also been clear that marijuana use isn’t a measure of morality. “A finding of a trace amount of drugs in one’s system does not mean that the employee is unproductive or about to engage in a workrelated crime,” Justice J. A. McDonald of the Federal Court of Appeal wrote in 1998, ruling that a TD Bank drug-testing policy for new hires was discriminatory.

Ottawa and the provinces should avoid getting mixed up in this contentious issue. A federal committee studying the topic reached an impasse this spring – and with good reason. There are already sufficient measures in place for companies to deal with impaired employees through existing provincial and federal occupational health and safety laws. Employers can discipline and dismiss employees who violate their drug and alcohol policies, so long as they don’t discriminate against those who are battling addictions.

Unlike in the United States, which began implementing drug-testing regulations in the 1980s, there’s no Canadian law that allows for mandatory screening of workers. (Canadian soldiers are a notable exception.) The legalization of recreational cannabis is not a reason for Ottawa to impose new testing requirements.

The fact is that drug tests are flawed. Exposure to second-hand smoke or consuming some medications can create false positives. Hair samples can be corrupted by dyes or chemical treatments. People with dark hair have a strike against them, simply because melanin helps bind drugs to their locks. Urine tests can detect marijuana use days after the high wears off. Moreover, a positive drug test doesn’t prove someone is impaired or an addict.

Drug screening does not improve workplace safety, but it’s guaranteed to destroy morale. It’s also a surefire way to invade workers’ privacy while creating opportunities for abuse. There’s a risk that companies could use employee samples to also test for pregnancy, diseases, disabilities or prescription medications.

Companies have no business snooping on employees’ private lives, and there’s no reason to treat legal cannabis any differently than alcohol. It will still be illegal to drive impaired and unseemly to get high at work. If adults want to enjoy a joint on their own time, they should be able to do so without judgment or the fear that their employers are becoming de facto narcs.