This story is part of a partnership between MedPage Today and VICE News.

California became Thursday the fifth US state to allow "aid in dying," giving terminally ill patients the right to seek medical help the end their own lives.

Gov. Jerry Brown signed the California End of Life Option Act in October, and it went into effect Thursday. Participating patients will need to have no more than six months to live; be able to self-administer the drug, and submit two oral requests for an aid-in-dying prescription at least 15 days apart, followed by a written request for this prescription signed in the presence of two witnesses.

California joins Oregon, Washington, Vermont and Montana.

"Tomorrow is a monumental day for Californians suffering from terminal diseases," Matt Whitaker, who directs California's branch of the aid in dying organization Compassion and Choices, said in a statement released Wednesday. "This law is spurring open, honest conversations among Californians families about end-of-life care options that were not taking place before."

Whitaker mentioned Jennifer Glass and Christy O'Donnell, two terminally ill women who fought for the right to die on their own terms. Glass died last summer after undergoing several days of palliative sedation, in which she was sedated and not given fluids or nutrition until she passed away. O'Donnell died in February.

"I'm doing everything I can to extend my life," Glass said at the press conference introducing the End of Life Options Act in early 2015. "No one should have the right to prolong my death."

Although right-to-die advocates in the state are celebrating, Catholic groups have opposed the law and some hospitals have already told reporters that they will "opt out."

"What some mistakenly consider a newfound 'freedom,' will inevitably become a duty for others," the California Catholic Conference of Bishops said in a press release. "By allowing doctors to prescribe a lethal dose of drugs to their patients, California is embarking on a dangerous course."

A coalition called Californians Against Assisted Suicide includes disability groups that fear patients won't get disability services and could be coerced into assisted suicide, as well as mental health professionals who fear that distraught patients will be granted aid in dying instead of being referred to psychiatric or therapeutic caregivers.

Oregon passed the first bill establishing aid in dying more than 20 years ago, but the movement had been slow to spread throughout the country. Then, a dying California newlywed named Brittany Maynard brought it to national attention.

Videos of Maynard telling her story of moving from California to Oregon to legally end her life went viral. According to Barbara Combs Lee, president of the nonprofit organization Compassion and Choices, Maynard's testimony had a game-changing impact on the public's perception of end-of-life decisions.

"Because Brittany was so charismatic and compelling, her story was personal to everyone," Combs Lee told VICE News in August. "She had that effect on everyone who watched her video and followed her story. For all those people, all of the sudden an issue that was abstract became personal and concrete."

According to a May 2015 Gallup poll, 68 percent of Americans support aid in dying — up from 58 percent the year before.

More than 11 million people have watched Maynard's first YouTube video, which was posted last October. When her story took off, she worried that she was already too sick to make a difference, her husband, Dan Diaz, told VICE News last summer. He's since advocated for aid in dying on her behalf.

The day Maynard chose to die, he recalled, she drank the medication surrounded by friends and family at home and fell asleep in about five minutes.

"The whole time, she could just look to people in the room and say, 'I love you. It's okay,' " he said. She died roughly a half hour later. "It was gentle. It's what she wanted."

Had the tumor killed her instead, she would have been blinded, paralyzed, and in terrible pain, Diaz added, calling the ordeal "torture."

Groups oppose aid in dying for religious reasons and because they fear it will be abused. The American Medical Association opposes it because "fundamentally incompatible with the physician's role as healer, would be difficult or impossible to control, and would pose serious societal risks."