PROVIDENCE — As expected, Governor Carcieri yesterday vetoed medical marijuana legislation. And Democratic House leader Gordon Fox said he believes state lawmakers will override that veto.

“I support efforts to provide effective pain management to persons suffering from debilitating conditions, but not in a way that violates federal law and ignores the drug approval process as established by the Food and Drug Administration,” Carcieri, a Republican, said in his veto message.

He said the legislation “could potentially subject Rhode Islanders to federal prosecution, while significantly complicating the responsibilities of state and local law enforcement officials.”

But last month, 51 of 75 House members endorsed the measure. Forty-five votes, or three-fifths, are required to overturn a veto.

The bill, known as the Edward O. Hawkins and Thomas C. Slater Medical Marijuana Act, calls for permanently extending the medical marijuana law, which was due to expire this year under a sunset clause.

“I fully expect that we will place a vote to override the governor’s medical marijuana veto on the floor calendar before the end of our session,” Fox said in a statement anticipating the veto. A prior vote on the bill “made it clear that there is an overwhelming majority in the House willing to remove the sunset clause on this compassionate legislation.”

A patient diagnosed as having a debilitating medical condition would be allowed to possess up to 12 marijuana plants and 2.5 ounces of marijuana. An adult who has agreed to help an ill person’s medical use of marijuana — a caregiver — could have 12 plants and 2.5 ounces of marijuana for each of up to five qualified patients.

The state Department of Health would supervise the proc

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