Kansas’ highest court appeared receptive Thursday to declaring for the first time that the state constitution recognizes abortion rights, with a majority of the justices skeptical of the state’s argument against the idea as it defended a ban on a common second-trimester procedure.

The state Supreme Court heard arguments in a lawsuit filed by Kansas City-area father-daughter physicians against a 2015 first-in-the-nation law that has become a model for abortion opponents in other states. The key issue is whether the Kansas Constitution protects abortion rights independently of the U.S. Constitution, which would allow state courts to invalidate restrictions that have been upheld by the federal courts.

Abortion opponents fear that such a decision by state courts could block new laws or invalidate existing ones even if President Donald Trump’s appointments result in a more conservative U.S. Supreme Court. Janet Crepps, an attorney for the New York-based Center for Reproductive Rights, which is representing the doctors, argued that it’s important for Kansas residents to know what rights their constitution protects.

“The federal constitutional protection seems to ebb and flow with the political tide,” Crepps said.

Abortion-rights supporters contend broad language in the state constitution’s Bill of Rights protects a woman’s right to obtain an abortion. The Bill of Rights says residents have “natural rights” including “life, liberty and the pursuit of happiness” and that “free governments” were created for their “equal protection and benefit.”

The state argues there’s no evidence that when the constitution was written in 1859, its drafters contemplated the issue in a legal environment in which abortion generally was illegal.