Vermont Gov. Peter Shumlin has signed a bill into law that has legalized physician-assisted suicide for terminally ill patients who want to end their lives.

The governor’s signature has made Vermont the fourth US state to legalize assisted suicide, which Shumlin hailed as a victory for the few terminally ill Americans whose suffering surpasses their will to live.

“This bill does not compel anyone to do anything that they don’t choose in sound mind to do,” he said before signing the End of Life Choices law on Monday. “All it does is give those who are facing terminal illness, are facing excruciating pain, a choice in a very carefully regulated way.”

The state legislature last week approved the legislation, which allows anyone over the age of 18 with an “incurable and irreversible disease” and a maximum of six months to live to acquire a prescription for lethal drugs.

The measure requires at least two doctors to make the medical determination whether or not a patient qualifies for physician-assisted suicide. A patient wishing to end their life must make an initial oral request at least 15 days before receiving lethal drugs, and a written and oral request to die 48 hours before receiving them. Two “disinterested” individuals that are neither related to the patient nor the healthcare providers must witness these requests.

The law takes effect immediately, and state officials are now scrambling to pull up guidelines for doctors who plan to administer lethal drugs.

Bob Ullrich, a board member of the advocacy group Patient Choices Vermont, has been pushing for the legalization of assisted suicide for more than 10 years. He stood beside Gov. Shumlinon Monday, witnessing the governor sign the bill into law.

“It means peace of mind and comfort to a lot of people, including me, that I hope no one ever has to use the law, but to know every day of your life that it’s there should such an occurrence happen,” he told The Burlington Free Press after the signing.

Vermont is the first state that has passed this measure through the legislative assembly. In Oregon and Washington, assisted suicide was approved through general elections, and in Montana, the Supreme Court ruled in 2009 that physicians may aid terminally ill patients who are on their death beds already.

Across the US, eight other states have introduced bills allowing physician-assisted suicide, while two states introduced bills banning the procedure, according to information from the Death with Dignity National Center.

But while Vermont’s governor celebrated the signing of the bill – which coincidentally fell on his father’s 88thbirthday – the signing ceremony also drew out numerous opponents.

The Vermont Alliance for Ethical Healthcare, a group that opposes the new law, said it will now focus its efforts on helping health care providers find alternative ways to health the terminally ill.

“We now have state-sanctioned suicide in Vermont,” Edward Mahoney, president of the group, told Reuters. “If the state won’t protect Vermonters, we will try.”

Carrie Handy, a Vermont resident and member of True Dignity, said her group will now try to help patients who feel pressured into requesting their own deaths.

“We would have liked to defeat the legislation,” Handy told The Burlington Free Press. “Now that it’s been enacted we feel our role needs to be for the time being serving as a watchdog organization. We do feel this legislation puts vulnerable people at risk.”

But even though doctor-assisted suicide is now legal in Vermont, experts estimate that very few people will turn to this option. Vermont Health Commissioner Dr. Harry Chen told AP that he only expects doctors to write out 10 to 20 lethal prescriptions each year, with an even smaller number of patients actually choosing to self-administer the drugs.

Chen’s estimate comes from figures in Oregon, where 673 patients died from ingesting lethal barbiturates prescribed between 1997 to 2012. The most ever prescribed in a year was 77, which occurred in 2012.

“It’s used by a very small number, but it brings comfort to a much greater number knowing it’s there,” Chen said.

But supporters in Connecticut and New Jersey – states that have recently considered similar bills – hope that Vermont’s decision will influence other US legislatures in passing similar measures.

"Vermont's law reflects another normalization of the practice of aid in dying in the practice of medicine," Kathryn Tucker, director of legal affairs at Compassion and Choices, told Reuters. "Support for patients to be empowered and choose aid and dying is growing. So I think this is an important step in moving that forward."