Chief Magistrate Judge Maria-Elena James heard arguments from local and federal officials locked in a battle over the Harborside Health Center in Oakland, Calif., which has more than 108,000 members in its patient collective. She made no immediate ruling Thursday, the Los Angeles Times reported.
In the fall, Oakland was the first municipality to sue federal prosecutors, attempting to block federal agents from closing Harborside.
Thursday's hearing was the first since Colorado and Washington voters in November legalized small amounts of marijuana for recreational use, the Los Angeles Times reported.
Medical marijuana advocates said they hope James remembers the votes when she decides whether to order an immediate stop to all Harborside sales.
"They can sell popcorn there. They can sell candy there. We're just asking that the court advise Harborside that they cannot use the property for any illegal purpose," Assistant U.S. Attorney Arvon Perteet told James.
"Clearly if people think that marijuana should be legalized completely in at least two states, then from our vantage point it should at least be legal for patients who need it for medical use," said Joe Elford, chief counsel for Americans for Safe Access, which spoke on behalf of six Harborside patients.
If Harborside is shut down, thousands of patients will be driven into the illegal cannabis market, pro bono attorneys representing Oakland said.
Federal prosecutors asked James to remove the city from the case, maintaining the U.S. Supreme Court ruling bars a "medical necessity" defense in federal court and federal officials had reserved the right to take action against any dispensary.
"There is a strong public interest in the enforcement of federal law, as well as in the protection of the public from drugs that federal regulatory authorities have not approved for medical use," prosecutors said in court papers.