A convicted marijuana grower was sentenced to one day in prison and fined $1,000 by a federal judge today, the most lenient sentence allowed under law.

The defendant, Ed Rosenthal, had faced a possible sentence of 100 years in prison and a potential fine of $4.5 million for his conviction in January on felony charges of marijuana cultivation and conspiracy.

"We are all delighted with what we view as as fair and just a sentence that could be imposed under the circumstances of Ed having suffered a conviction," one of Mr. Rosenthal's lawyers, Dennis P. Riordan, said.

Federal authorities arrested Mr. Rosenthal last year for growing marijuana to be sold for medicinal uses under the auspices of the City of Oakland's medicinal marijuana ordinance.

Though the Oakland ordinance is permitted under a 1996 California state proposition, there is no provision for growing marijuana under federal drug laws.

The judge, Charles R. Breyer of Federal District Court, had not allowed Mr. Rosenthal to raise medicinal marijuana as a defense, leading some jurors to later complain that they had been misled by the court. After convicting Mr. Rosenthal, several jurors requested a new trial, and when that failed, wrote to Judge Breyer urging leniency.

At a hearing today, Judge Breyer said it was reasonable to conclude that Mr. Rosenthal had believed he was acting legally. By making that determination, the judge was able to skirt some minimum sentence requirements, which could have put Mr. Rosenthal in prison for at least five years, his lawyers said.