Updated

Voters in several states decided ballot initiatives Tuesday that should weigh significantly on the future of such controversial medical issues as stem cell research and the medical use of marijuana.

In California, voters approved a measure to provide $3 billion in state funding for controversial stem cell research. The move could push the state past federal limits on stem cell funding and position California at the forefront of U.S. research in the field.

Republican Gov. Arnold Schwarzenegger backed the initiative, Proposition 71.

Many scientists believe stem cells hold vast promise for treating an array of diseases from diabetes to Parkinson's. Stem cells can potentially grow into any type of human tissue and scientists hope to be able to direct the blank cells to grow into specific cell types needed for transplant.

But even the most enthusiastic supporters acknowledge that such results are many years away.

While California was the only state to tackle the stem cell issue, voters in several states were presented with ballot initiatives legalizing medical marijuana. Montana became the 10th state to legalize marijuana for medical purposes Tuesday, passing a measure that allows patients to grow or possess limited amounts of the drug with a doctor's approval.

Alaskans defeated a more ambitious proposal to decriminalize pot altogether. In Oregon, voters rejected a measure that would have dramatically expanded its existing medical marijuana program by allowing patients to buy the drug from state-regulated sources.

Alaskans are already allowed to possess up to 4 oz of marijuana in their homes under a state court order, but the new measure would allow marijuana transport and also clear the way for regulation and taxation of the drug.

Missouri voters living in the city of Columbia are also voting on a pair of propositions authorizing medical marijuana.

In Massachusetts, voters in 12 districts cast ballots supporting nonbinding measures that could liberalize laws on marijuana possession. Bay-area ballots in Oakland and Berkeley, Calif., also included local questions expanding access to already-legal medical marijuana.

Medical marijuana has become a flash point between federal drug officials and legalization activists. John Walters, who directs the White House Office of National Drug Control Policy, has sharply criticized medical marijuana policies for sending a mixed message to youths about the dangers of illegal drugs. He has also lobbied against medical marijuana initiatives in various states, sparking accusations of illegal advocacy from legalization supporters.

Rob Kampia, executive director of a pro-legalization group called the Marijuana Policy Project, said his organization spent $2.1 million on statewide initiatives, including $110,000 spent getting the 22,000 signatures required for the Montana ballot.

Web MD's Todd Zwillich and the Associated Press contributed to this report.

SOURCES: Robert Kampia, executive director, Marijuana Policy Project. Alaska 2004 state ballot. Montana 2004 state ballot. Ann Arbor, Mich., 2004 ballot. California 2004 state ballot. Rosalie Pacula, PhD, an economist at the Drug Policy Research Center, part of the RAND Corp.