ROCHESTER, N.Y. (WHAM) — Guidance from the New York State Department of Labor says most companies can no longer require employees to be tested for marijuana or discriminate against employees for use of the drug outside of the workplace.

For most jobs in the public and private sectors, companies are not allowed to test employees for cannabis.

Employment Lawyer Kim Harding says the new law also prohibits making marijuana use outside of work a fireable offense in most cases, whether you work in the office or at home.

That's the biggest change that the law created, and that's confirmed in the guidance. So, employers that really have to update their policies and make sure that their drug abuse and drug testing policies are now compliant with the law," said Harding.

However, since marijuana is still illegal federally, not every occupation is covered by state law.

Who this won't apply to is really employees of the federal government, and that would include likely federal or that would include federal law enforcement, other groups that are excluded are commercial drivers, railroad operators, school bus drivers," Harding explained.

Businesses can make their own policies when it comes to cannabis use during work hours or on company property.

But with testing now out of the question, it will be tougher for businesses to prove if someone is using while on the clock.

"They cannot take action, merely on the basis that someone smells of cannabis, but they can maintain general grooming standards, and of course can continue to maintain performance standards and try to hold people accountable for their work, irrespective of whether they suspect cannabis use," said Harding

A company can ultimately fire employees that exhibit reckless behavior as a result of being impaired by cannabis.