Rosenthal, 64, was convicted in federal district court in San Francisco in 2007 of three counts of conspiring to grow marijuana and growing marijuana in an Oakland warehouse.
He was sentenced to one day already served in prison.
Rosenthal's appeal will be heard this morning by a three-judge panel of the 9th U.S. Circuit Court of Appeals, which is expected to issue a written ruling at a later date.
Rosenthal claims his trial was unfair because the jury was not allowed to hear evidence that he believed he had been deputized by the city of Oakland to carry out its medical marijuana program.
If Rosenthal wins a new trial, it would be his third. He was convicted in an earlier trial in 2003, but that conviction was overturned by the appeals court on grounds of juror misconduct.
Rosenthal's attorney, Michael Clough, said Tuesday that even though his client was sentenced to only one day in prison, he is appealing to clear his name and remove the designation that he is a convicted felon.
Clough said that Rosenthal doesn't fear that he is risking a longer sentence because both the appeals court and the trial judge have approved the one-day penalty.
Outside of court, Rosenthal has claimed he was growing starter plants for patients needing medical marijuana. But he was never permitted to make that argument in federal court because U.S. drug laws make no exception for state medical marijuana laws.