Already nervous, some doctors who had signed up promptly backed out when Sessions reversed the hands-off policy of the Obama era.

“I know of two who had already registered who decided not to take the risk after all,” Ransom said. “One of them had already written recommendations for several patients.”

The problem is not limited to Maryland, one of 28 states that has legalized medical marijuana. The reluctance of doctors, particularly on the East Coast, to embrace it has become the final and highest hurdle in the push to normalize the drug, advocates say.