The Oklahoma Supreme Court on Monday unanimously ruled that a ballot measure to completely prohibit abortion was "clearly unconstitutional."

The American Civil Liberties Union and the Center for Reproductive Rights filed a lawsuit against the ballot measure, which would have amended the Oklahoma Constitution to grant fertilized eggs and embryos the same constitutional rights as people.

“By their own admission, the proponents of this initiative aim to strip women and families of their established right to decide whether and when to become pregnant and carry a pregnancy to term,” Ryan Kiesel, executive director of the ACLU of Oklahoma, said in March. “This initiative insults Oklahoma women’s intelligence and dignity by denying access to basic health services.”

Legislation similar to the "fetal personhood" ballot measure passed in the Oklahoma Senate in February by a 34-8 vote. However, Oklahoma House Speaker Kris Steele and the State House Republican Caucus decided not to bring the bill to the House floor for a vote.

The pro-life Christian group Personhood USA and its state affiliates have campaigned to place "fetal personhood" initiatives on the November ballot.

The Colorado Supreme Court ruled in March that a proposed "fetal personhood" amendment to the state’s constitution could be placed on the 2012 ballot. In contrast, a Nevada judge ruled in December that the ballot initiative was so vague that backers were not allowed to circulate it among voters.

A similar constitutional amendment was rejected by more than 55 percent of Mississippi voters last year.