There's no shortage of online advice for beating an employer drug test meant to check for marijuana use, whether it's getting a friend to take the test, taking supplements, or flushing chemicals out of your system.

But a desperate search for acing a drug test may soon become a thing of the past for some workers. In 44 states and the District of Columbia, marijuana is legal in some form. As a result, some workplaces and state governments are relaxing their rules regarding drug testing. Employers and proponents of altering zero-tolerance drug policies say it's OK for their workers to use cannabis on their own time, as long as they're not using it at work and aren't impaired while working.

As cannabis legalization advocates try to push for the changes, they are running up against critics who say permissive attitudes about marijuana open the door to workers endangering themselves or others and shouldn't happen at a time when federal regulators haven't cleared marijuana products.

"I think it's incredibly dangerous," said Kevin Sabet, president and CEO of Smart Approaches to Marijuana, which opposes legalization of the drug but not its criminalization. He gave examples of workplaces where people carry heavy equipment or work in factories. "Would you want your surgeon, pilot, or bus driver stoned? I think we have to err on the side of caution," he said.

In most states, employers can fire people or recant on a job offer when people test positive for marijuana and are allowed to have rules requiring drug-free workplaces because the drug is still illegal under federal law.

But other places are changing it up. Starting in May, New York City employers can't force a prospective employee to undergo a drug test to check for marijuana use, except if there are safety concerns. Nevada protects job applicants against being turned down because of testing positive for marijuana use. In Congress, a House bill would keep federal workers from getting fired for using marijuana if their state has legalized it.

"There is definitely a lot of movement going in the right direction as the stigma is eroding about cannabis use," said Morgan Fox, spokesman for the National Cannabis Industry Association. "A lot of consumers, regardless of personal, medical use, experimentation, or doing it for a while, don't want to be discriminated against by potential employers because of legal activities they decide to participate in when they're not at work."

At least 16 states and Washington, D.C., have rules shielding workers who take marijuana for medical reasons, and California may be next. Democrat Rob Bonta, a state assemblyman representing Oakland, introduced legislation in February that would bar employers from turning away workers who are taking marijuana for medical reasons or from firing them just because they test positive for marijuana.

"To be discriminated against by your employer because of the type of medicine you use is both inhumane and wrong," Bonta said in a statement when he released the bill. "Medical cannabis, as recommended by a doctor, should be given a similar 'reasonable accommodation' as all prescription drugs."

Because of safety concerns, the measure wouldn't apply to school bus drivers, pilots, or truck drivers. It also would not extend to protect people who are high at work, but those using marijuana on their own time. Employers would be allowed to request medical cards as evidence that workers are taking the drugs for medicinal reasons.

Even though workplaces have tested for marijuana use for some time, the technology for the test has never been reliable. One of the tricky parts about testing for marijuana is that a positive test result doesn't necessarily mean someone is impaired at that moment. THC, the high-inducing chemical in marijuana, stays in the body for a month after use.

In contrast, alcohol blood levels indicate how much someone has had to drink, and then, levels decline as that person gets sober. Proponents of marijuana legalization and regulation have long been frustrated by how the drug is treated with more scrutiny than alcohol, even though studies show that overdrinking is an issue with worker productivity.

Some employers are changing drug testing rules without the push of state lawmakers. According to a survey from Simply Hired, 55.1% of hiring managers don't drug test current employees for marijuana, and of those who do test, 38.9% say they do it less than in the past.

But Sabet says that states and employers should tread carefully because the marijuana available today is more potent than it used to be, and there's no consistent level THC for every product sold.

He worried that people would be affected after impairment in ways they might not realize. Because marijuana is still illegal under federal law, there haven't been robust, federally funded studies about the effects of all the different products available, including how they could help people who are sick.

"There is a big issue of people thinking if they're in a legal state that somehow the product is regulated well," Sabet said. "The reality is that we don't know what's in those products."