Colorado voters this fall will decide whether terminally ill people should be allowed to receive prescriptions for drugs to end their own lives.

The “Medical Aid in Dying” measure was certified Monday as having enough petition signatures to make ballots this fall.

Five other states have some law allowing the terminally ill to end their lives.

Oregon passed the first right-to-die law in 1998, followed by Washington, Vermont and, last year, California. Montana’s state Supreme Court ruled in 2009 that doctors could use a patient’s request for life-ending medication as a defense against any criminal charges.

Colorado’s version would require two physicians to agree that a person is terminally ill and has six months or less to live, is at least 18, and is mentally competent.

Similar measures have twice failed in the Colorado Legislature. Lawmakers from both parties said that the law could facilitate suicide in cases where a diagnosis may be wrong.

The suicide measure becomes the third citizen petition to make Colorado ballots. Voters will also decide a universal health care measure and a higher minimum wage.

The secretary of state is reviewing petitions for several more ballot measures, including a higher tobacco tax, a plan to replace presidential caucuses with presidential preference primaries, and two measures to change regulations on oil and gas drilling. Another pending measure would make it harder to put a ballot measure to voters, requiring more geographic diversity in the 98,000 or so signatures to put a proposal before voters.

Supporters of Colorado’s suicide measure had raised about $4.4 million by Aug. 1, according to state filings. Opponents including the Colorado Catholic Conference had not reported any fundraising by Aug. 1.