(CNN) -- The U.S. Supreme Court declined on Monday to review an abortion-related appeal, a sign the justices were not eager to jump into the contentious social issue.
The case dealt with the constitutionality of state "personhood" laws that say life begins at conception, and would give human embryos the rights and privileges of citizens.
Initiative Petition 395 is a proposed ballot measure to amend Oklahoma's state constitution, but was unanimously struck down by the state's supreme court.
Those justices said the measure, if approved, would unconstitutionally ban access to abortions, and concluded that defining a fertilized human egg as a person "is clearly unconstitutional."
The high court gave no reason why it decided not to review the Oklahoma case.
Supporters of the measure believe voters should be given the right to decide an issue like defining life, and said it was unfair for the courts to block the law before it was enacted.
Opponents counter it would essentially block abortions even in cases of rape, incest, or when the mother's life was in danger. They also said it would severely restrict use of contraception and in vitro fertilization.
A bill similar to Oklahoma's is pending in the Virginia legislature. Voters in Colorado and Mississippi have rejected "personhood" ballot initiatives in recent years.
Many backers had hoped to use such "gateway" measures to force another Supreme Court showdown over the landmark 1973 Roe v. Wade ruling legalizing abortion.
The case is Personhood Oklahoma v. Barber (12-145).