NEW PORT RICHEY — A self-described "medical marijuana missionary" from Shady Hills pleaded no contest to pot cultivation charges Monday after a judge rejected his medicinal necessity defense.

Alfred Robinson, 59, and his lawyer, Michael Minardi, came to the west Pasco courthouse fully prepared to go to trial, but prosecutors filed a last-minute motion challenging the basis for Robinson's defense. Circuit Judge Pat Siracusa granted the motion, effectively slicing the legs off Robinson's case.

"I don't know whether I'm happy not being in jail," Robinson said outside the courtroom. "I can't do my medicine. They're forcing me to suffer or go back on prescription drugs."

Robinson was arrested in July after Pasco deputies found two marijuana plants on the 5 acres where he lives. He had more plants, he said, but he burned them before deputies arrived.

Robinson, who's had several marijuana arrests dating back to 1979, said he uses the drug to alleviate severe back pain. He has degenerative disc disease, and the court file says he also suffers from anxiety, sleeplessness, depression and chest pains.

Siracusa is the third judge to hear the case. At a hearing in January, Circuit Judge William Webb had Robinson put in handcuffs and threatened to hold him in contempt if he wore a marijuana T-shirt to court again.

"I'm a patient, not a criminal," it said.

Minardi filed a motion to disqualify Webb, citing First Amendment concerns and a fear that Robinson wouldn't get a fair trial.

Circuit Judge Mary Handsel handled the case next. Robinson wore his shirt once and got away with it, but the second time, he was told to cover it up.

On Monday, some of Robinson's followers wore pro-pot shirts to court and several petitioners outside the courtroom collected signatures for legalized medical marijuana. Across the state, supporters are in the process of gathering signatures to get a constitutional amendment before Florida voters in 2014 to decriminalize marijuana for medical use.

"The laws in effect in the state of Florida are the laws I have to enforce," Siracusa told Robinson. "If the law changes, then I'm going to follow that law."

He sentenced Robinson to three years of probation and gave him a waiver on his first drug test. He added a stipulation that if Robinson were to move to a jurisdiction where pot is legal, he wouldn't be in violation. Also, if the law were to change, Siracusa said he would re-evaluate Robinson's situation.

Minardi said he's disappointed and plans to appeal.

"We would've won with that argument," Minardi said. "It's very sad that a person was not allowed to exercise his constitutional right to go before a jury."

For Robinson, the outcome is personal. The marijuana, he said, is the only thing that keeps him from feeling chronic pain without clouding his mind and affecting his health. He wants to keep working to change the law, although it may be more difficult now that he's only allowed to leave the county for probation-specific purposes.

"I was born and raised in St. Pete. I can't really afford to move to a marijuana state," he said. "I guess I'm going to have to suffer, right?"

Jon Silman can be reached at (727) 869-6229, jsilman@tampabay.com or @Jonsilman1 on Twitter.