Adult-use recreational marijuana will legally be on sale Thursday in New Jersey.

Jersey City Mayor Steven Fulop says that police officers in his city are not able to consume marijuana, even if they are off duty. But this goes against a directive from state Attorney General Matt Plakin, who says that off-duty police officers are allowed to use cannabis.

Fulop says that he supports legalization. But he says that since there is not a reliable way to test when a person last consumed marijuana, he cannot allow his officers to partake.

“It’s unclear if they were smoking an hour before the job, they had a gummy on the job or two weeks ago,” says Fulop.

He says that if it is a situation where officers have to use their firearms, that lack of clarity could erode community trust.

Other professions could see some of these conflicts as well.

“And until Congress acts and the federal government begins to wade into this measure, there are going to be some uncertainties in the law,” says Bill Caruso, founding member of NJ United for Marijuana Reform.

Caruso says it is best for potential marijuana customers to know the rules for where they work.

And some may also be wondering where recreational marijuana can be used. Most experts say to think of it like alcohol.

“You can’t walk down Main Street with a bottle of beer in your hand,” says Caruso.

He says that the industry is modeled for adults to use marijuana at home after they buy it legally.