"The Legislature knows how to say, 'Thou shalt not ban dispensaries,'" Justice Ming Chin told a lawyer for a dispensary in the city of Riverside.
"They did not say that," Chin said.
The Riverside dispensary, known as the Inland Empire Patient's Health and Wellness Center, is challenging a city zoning law that prohibits such facilities.
While the case concerns one dispensary, the court's eventual ruling will affect cities and patients' access to marijuana throughout the state.
More than 180 California cities and 20 counties currently ban dispensaries, according to Kris Hermes, a spokesman for the advocacy group Americans for Safe Access. Ten counties and 44 cities, including San Francisco, Oakland, Berkeley and Santa Rosa, have regulations allowing them.
The court's seven justices took the case under submission after hearing an hour of arguments at a special session held at the University of San Francisco Law School to commemorate the school's 100th anniversary. The panel now has 90 days to rule.
The Inland Empire Center contends that two state laws that allow the use of medical marijuana and set guidelines for regulation mean that cities can regulate but not prohibit marijuana dispensaries.
"Land-use regulation does not give cities the power to ban what state law makes lawful," dispensary attorney J. David Nick argued to the court.
But Jeffrey Dunn, a lawyer for Riverside, argued that the state laws merely exempt certain patients and caregivers from prosecution and don't interfere with local governments' power to pass zoning measures to protect public health and safety.
Several of the justices appeared inclined to agree.
"The core of the case to me is really land use regulation and...the power invested in municipalities to regulate land use," said Chief Justice Tani Cantil-Sakauye.
Justice Joyce Kennard suggested that cities' land-use authority is more fundamental than the state medical marijuana laws because the zoning authority derives from the state Constitution.
"It is a pre-existing power, an extension of the police power," she said.
The two state laws are the voter-approved Compassionate Use Act of 1996, which protects seriously ill patients who use marijuana with a doctor's permission from being prosecuted; and the Legislature's 2003 Medical Marijuana Program Act, which sets guidelines for implementing the earlier law.
Justice Goodwin Liu told Nick, "The language (of the laws) doesn't seem to get you very far.
"This is a kind of limited liability" from state prosecution, Liu said, but "it says nothing about immunity from local sanctions and prohibitions."
Justice Kathryn Werdegar commented, however, that the purpose of the laws is to make marijuana available as a medicine, and said, "If all counties ban it, that purpose is thwarted."