Prosecutors and police officers say they still have fundamental questions about how to enforce the new law that takes effect Jan. 2 decriminalizing possession of small amounts of marijuana.

Many law enforcement officials strongly opposed the intensely debated Nov. 4 state ballot question that will turn possession of an ounce or less of marijuana into an offense on par with a traffic violation. Police and prosecutors say they are in the dark about many aspects of the law.

A high-ranking state judge sought to clarify some matters in a memorandum issued yesterday. But police and prosecutors said questions still abound, including what they should do with people caught with several joints who refuse to identify themselves, who will develop and fund a drug-awareness program required for violators under 18, and whether state-run laboratories that test drugs seized in criminal cases will continue to do so for small quantities of marijuana.

"I think there are a lot more questions than answers right now," Lawrence Police Chief John J. Romero said of the law. "I don't think anybody knows how this is going to play out."

Berkshire District Attorney David F. Capeless, president of the Massachusetts District Attorneys Association, said state officials have yet to address other unexpected questions, including whether police chiefs can discipline officers who light up a joint after work.

"I'm not suggesting that officers are doing it," he said. "But what you're doing, whether it's officers or other public employees - transportation workers, bus drivers, teachers - you're removing a disincentive by saying: 'We won't be able to do anything to you. You won't get disciplined for this. It won't mean your job. It may mean a $100 fine.' "

In a letter last month on behalf of the district attorneys, Capeless urged Governor Deval Patrick to ask the Legislature to delay the effective date of the new law. But a spokesman for the state's Executive Office of Public Safety and Security said yesterday that Patrick will not do that, even though the governor opposed the ballot question.

Terrel Harris - a spokesman for the Office of Public Safety, which is responsible for setting up the new system of civil penalties - acknowledged that time is running out until the law goes into effect and said the office will issue its own guidelines for law enforcement officials next week.

"We are looking at this issue from every conceivable angle," he said. "We realize that the deadline is rapidly approaching, but we want to get it right."

Thomas W. Nolan, an assistant professor of criminal justice at Boston University and a former Boston police lieutenant who was featured in a television ad supporting Question 2, characterized the complaints of law enforcement officials as inflexibility.