A group that seeks to establish legal rights for embryos is asking the U.S. Supreme Court to allow a state ballot initiative on the issue to proceed.
The Oklahoma Supreme Court, in April, stopped the circulation of a ballot petition that would define a fertilized human egg as a person under state law, effectively banning abortion.
The court argued that women have a right to abortion under the Supreme Court's ruling in Roe v. Wade and declared the ballot measure unconstitutional and void.
"This is about the fundamental rights of people in a state to decide for themselves what the law in their state should be," said Steve Campton, a lawyer for the group.
In its petition, Personhood USA claims the Oklahoma Supreme Court violated citizens' First and 10th Amendment rights by voiding the ballot petition.
The group also asked the U.S. Supreme Court to issue a ruling that would clarify several contradictory lower court decisions.
"There are wildly different approaches in how [states] regulate and respond to" efforts of direct democracy, Campton said. "The court needs to weigh in here and clarify the conflict between the lower courts."
Keith Mason, president of Personhood USA, said the petition "is fighting ... to literally change the culture of this nation."
Oklahoma's ballot measure would have given "inherent rights" to anyone from the "beginning of biological development to the end of natural life."
Abortion-rights supporters said it would end abortion in the state, outlaw forms of birth control and threaten the practice of in-vitro fertilization.