LOS ANGELES — A federal judge here Monday postponed the sentencing of a man convicted of running a medical marijuana dispensary and asked the Department of Justice to clarify its revised position on such cases.

Attorney General Eric H. Holder Jr. said last week that federal authorities would not seek to prosecute medical marijuana dispensaries if the operations complied with state and local laws, a departure from the Bush administration policy that federal narcotics laws held sway. California is one of 13 states that allow the growth and sales of medical marijuana with a doctor’s recommendation.

“The judge said this statement raises more questions than it answers,” said Reuven Cohen, a lawyer for the defendant, Charles Lynch. “He said he needed an explanation, and he needed it from the Department of Justice, not the local prosecutor.”

Thom Mrozek, a spokesman for the United States attorney in Los Angeles, said that he could not comment on the specifics of the request by Judge George H. Wu, but that prosecutors “do believe that Mr. Lynch violated state law.”

Last August, a jury convicted Mr. Lynch on five counts related to running a dispensary and selling medical marijuana to customers under 21, considered minors under a federal statute that prohibits the sale of marijuana and other narcotics to minors. Mr. Lynch faces a minimum sentence of five years in federal prison.

The case has been widely followed by medical marijuana advocates since Mr. Lynch was arrested after a 2007 raid on his dispensary in Morro Bay, Calif.

Video from the local news in 2006 shows Mr. Lynch celebrating the dispensary’s opening. He is seen shaking hands with the mayor and flanked by local business leaders holding a banner emblazoned with “Morro Bay Chamber of Commerce.”

Supporters of Mr. Lynch came to the federal courthouse in downtown Los Angeles on Monday, but Judge Wu’s announcement was not cause for relief, Mr. Cohen said.

“He’s scared,” Mr. Cohen said of Mr. Lynch. “He’s an engineer with no criminal record. In a million years, he never thought that this is where he’d be.”

Mr. Cohen said Mr. Lynch “has not violated any state laws.”

Prosecutors convicted Mr. Lynch under federal statutes last summer. The issue of state law was not raised in the trial, Mr. Cohen said.

Mr. Mrozek said Monday that Mr. Lynch had violated state laws by selling marijuana for use by minors. “But this case involves a violation of federal law,” Mr. Mrozek said, “and that’s really all that matters.”

Mr. Mrozek said both sides would have a conference with Judge Wu on Friday, but prosecutors may not have a filing from the Department of Justice by then. The sentencing hearing has been postponed until April 30.