In both situations, the prevailing policy for employers remained one of zero tolerance, cited by 73% of employers in states that have fully legalized pot and 82% of those in states where only medical marijuana is allowed. Similarly, 54% of employers in medical-only states drug tested all job applicants, compared to 47% of employers in fully-legal states.

While a change in the drug's legal status in some states has led to some employers changing their policies on employee drug use, the great majority of employers have maintained their old rules. Only 29% of HR professionals located in states that have legalized the drug for recreational and medicinal use said their organization had modified its policy in response to the law. Among those in states that have only legalized medical marijuana, only 16% had.

Because federal law still prohibits all marijuana use, employers need not worry about lawsuits over their pot rules, according to Kathryn Russo, an attorney with Jackson Lewis in Long Island, N.Y.

“Many medical marijuana laws explicitly provide that employers need not accommodate marijuana use at work,” Russo told SHRM. “In Colorado and Washington, where there are both medical marijuana and recreational marijuana laws, lawsuits filed by employees using medical marijuana have been dismissed.”

The most common response to a violation of the drug policy was termination, according to the survey. That was the case for half of employers in medical-only states and 41% of employers in states where pot is completely legal. The next most common responses were mandatory drug counseling and written warnings.

Only 2% of employers surveyed in states where marijuana is fully legal said they allow employees to use the drug recreationally. Interestingly, HR professionals in states where it is fully legal were less likely to carve out exceptions to the rules for medical use (11%) than those in states where only medical marijuana is legal (22%).

In fact, of those employers that modified their policies recently, 37% had implemented stricter rules. Only 12% put in place less restrictive ones. Another 30% added language that specifically referred to marijuana without relaxing the rules.

There was also little indication that multi-state employers are changing their policies based on different laws in their various locations. Of the HR personnel surveyed, 62% said their company had operations in states with stricter laws, but 94% of the total group said the company drug policy was the same everywhere.