California is now the fifth U.S. state to legalize physician-assisted suicide.
Governor Jerry Brown signed legislation on Monday that allows doctors to prescribe lethal doses of drugs to terminally ill patients who wish to end their lives.
The law applies only to mentally competent people who have less than six months to live.
Supporters say the measure will allow dying patients the right to end their lives with dignity. But opponents, including the Catholic Church, fear vulnerable patients such as the poor, elderly and the disabled could be pressured to end their lives prematurely.
In a signed statement that he attached to the bill, Brown, a lifelong Catholic who once studied for the priesthood, said he consulted with many people on the merits of the bill, including a Catholic bishop and two of his own doctors.
"I do not know what I would do if I were dying in prolonged and excruciating pain," wrote the governor, who has been treated for both skin and prostate cancer." I am certain, however, that it would be a comfort to be able to consider the options afforded by this bill. And I wouldn't deny that right to others."
Brown's signing of the measure is a victory for advocates for physician-assisted suicide in California, who have tried and failed for several years to persuade enough lawmakers to approve such a law. Their efforts were boosted by the highly-publicized case of Brittany Maynard, a 29-year-old terminally ill woman who died by physician-assisted suicide after moving from California to the neighboring state of Oregon, where the procedure had already been legal.
Montana, Washington state and Vermont are the other U.S. states that have legalized physician-assisted suicide.