Planned Parenthood has sued Ohio over a law that bans dilation and evacuation abortions, one of the most common abortion methods.
Former Gov. John Kasich signed the ban last year on the procedure known as D&E, which is commonly used in second-trimester abortions. Similar laws have been rejected by the courts.
Planned Parenthood says the procedure is the safest abortion method after about 15 weeks of pregnancy and the only method provided in outpatient facilities. The lawsuit, which was also brought by the Women's Medical Center of Dayton, was filed Thursday in federal court in Cincinnati.
The lawsuit asks a judge to stop the law from being enforced and to declare it unconstitutional. The law was set to go into effect soon.
Ohio Right To Life, which supported the ban, issued a statement saying it was frustrated but not surprised. The group called the lawsuit "frivolous."
Attorney General David Yost said his office will "vigorously defend" the law's constitutionality.