Physician-assisted suicide bill was passed on Wednesday by state Assembly in California and is extensively believed to also be approved by the state Senate despite opposition from religious groups and advocates for the disabled.
The hard-fought measure was passed after gaining 43-34 following weeks of hearings and fiery debate, which is to authorise doctors to prescribe medication to the terminally ill patients to end their lives if taken.
"Imagine that it's one of your constituents, suffering in agonizing pain - their pain medication no longer works - then imagine that it's your father or your mother or your grandparents or your daughter," Assembly member Luis Alejo, a Democrat from Watsonville who supported the bill argued.
According to the bill, two doctors will have to verify that a certain patient had only six months to live prior to the prescription of the medication, emphasising that the bill makes it a felony to force or maneuver someone into taking certain medication.
Mentally ill patients will not be allowed to be given prescriptions.
In July, the bill was pulled for lack of support but then reintroduced last month as part of a special legislative session to deal with healthcare issues.
Oregon, Washington state, Montana and Vermont, all four states have made assisted suicide legal.
Last year, the matter made headlines when a terminally ill 29-year-old cancer patient, Brittany Maynard, moved from California to Oregon to take advantage of that state's law.
The bill won the support of the state Senate in June after Maynard's death, but the bill then crashed in the assembly Health Committee, due to heavy opposition from the Catholic Church, disability rights advocates and others.
The bill is now in full hands of the Senate, where it is expected to pass.
The legislature is known to pass regular session bills by midnight on Friday, but lawmakers may push to stay longer in an attempt to handle special session measures.
Polls show consistent support for such a measure in California, and in May, the California Medical Association changed its longstanding opposition to a neutral stance.