“The system we have inherited can best be described as medical marijuana in name only,” Mr. Murphy said during an event in Trenton. “With a hostile administration tugging the strings of state bureaucracy, the ability of dispensaries to open has been slow-footed. Doctors have faced stigmatization for participating. And nonsmokable and edible products that could benefit patients have been blocked from the market.”

Since the law was enacted, only five dispensaries have opened in New Jersey, and about 15,000 people have access to medical marijuana. Mr. Murphy drew a contrast with Michigan, which he said had given 218,000 people access to medical marijuana in a similar time frame.

“The roadblocks put in place by the past administration mean that the law’s spirit has been stifled,” Mr. Murphy said. “We’re not much further along in responding to the needs of patients than we were in January of 2010.”

Mr. Christie, who made much of his focus in his final year in office combating the opioid epidemic, viewed marijuana as a “gateway drug” and was strongly opposed to any type of legalization. Medical marijuana is often prescribed to help patients cope with chronic pain, among other ailments, and it was recently allowed as a treatment for post-traumatic stress disorder in many states, including New Jersey and New York.

During his campaign for governor, Mr. Murphy framed the full legalization of marijuana as a social justice issue. He argued that legalization would help reduce low-level drug prosecutions, which often ensnare black and Latino defendants in disproportionate numbers, and that it would decrease the state’s prison population.