Marijuana advocate Ed Rosenthal lectured a federal judge Friday before being sentenced to a day in jail -- which he has already served -- for growing pot plants for medicinal use.

"I am proud of what I did. I know I have done nothing wrong,'' Rosenthal told U.S. District Judge Charles Breyer. Referring to the two juries that convicted him of violating federal drug laws without hearing evidence that the marijuana was intended for medical use, Rosenthal said, "You have now hurt 24 jurors. ... You left them feeling guilty about their unwitting role in these faux trials.''

Breyer said Rosenthal could take his grievances to the federal appeals court that overturned his first conviction. The judge also issued a written decision rejecting Rosenthal's claims that he was denied a fair trial because evidence about medical marijuana was excluded and more than half the prospective jurors were dismissed because of their views on the issue. Rosenthal told reporters he would appeal the conviction.

Rosenthal, 62, of Oakland is an authority on marijuana cultivation, a former columnist for High Times magazine and a longtime advocate of marijuana legalization. Arrested in 2002 after federal agents seized more than 3,700 plants at his Oakland warehouse, Rosenthal was convicted the following year of growing marijuana, conspiracy and maintaining a building for illegal cultivation. The appeals court overturned that conviction on the grounds of misconduct by a juror who called a lawyer for advice during deliberations. Rosenthal was convicted by another jury on May 30.

The charges normally carry a sentence of at least five years in prison. But Breyer imposed only a one-day sentence after the first trial, saying Rosenthal had believed he was acting legally because Oakland had designated him its agent in the city's medical marijuana program.

An attempt by prosecutors to add charges of money-laundering and tax evasion for the second trial was rejected by Breyer, who said the government was retaliating for Rosenthal's successful appeal and his criticism of the case. Prosecutors proceeded with the retrial but conceded they could not seek additional punishment.

In both trials, Breyer barred evidence that the marijuana was intended for medical use under Proposition 215, the 1996 California initiative allowing patients to use the drug with their doctor's approval. He agreed with the prosecution that the evidence was irrelevant under federal law, which prohibits the possession, cultivation and distribution of marijuana, and does not recognize any legitimate use for the drug.

In his written ruling Friday denying a new trial, Breyer said he had not excluded jurors for holding particular viewpoints on medical marijuana, but dismissed only those who said they could not judge the case impartially. He also said his rulings on medical marijuana evidence were upheld by the appeals court that overturned Rosenthal's first conviction.