WASHINGTON — The American Civil Liberties Union filed a lawsuit on Wednesday challenging Ohio's six-week ban on abortion, opening up the latest front in a multistate legal fight over laws that ban abortion after a fetal heartbeat is detected.

Republican Gov. Mike DeWine signed one of the most restrictive abortion laws in the country in mid-April. The law, called “heartbeat legislation,” bans nearly all abortions after the fetus’s heartbeat can be seen or heard, usually after about six weeks of pregnancy — before most women are aware they are pregnant. The law also has no exemptions for rape or incest.

Ohio was the sixth state to adopt a six-week ban, joining Georgia, Iowa, Kentucky, North Dakota, and Mississippi, but these laws have either been blocked in court or haven’t taken effect yet. The Ohio law is set to take effect July 10; the ACLU is seeking an immediate court order delaying the start date while the lawsuit goes forward.

The ACLU, which filed the lawsuit on behalf of Planned Parenthood and other reproductive health providers on Ohio, estimates that the state’s law would prohibit 90% of abortions performed in the state. The group is arguing that the law violates women’s right to privacy under the Fourteenth Amendment.

Health care providers who violate the Ohio law would face up to a year in prison and a $2,500 fine, and they could face even stiffer fines from the state medical board and lose their license.

Ohio’s legislature passed similar measures twice before, but they were vetoed both times by the state’s former Republican governor John Kasich. This session, the state’s Republican legislators passed the bill again, confident their new governor, DeWine, would act in their favor.

This kind of legislation isn’t unique to Ohio. Model heartbeat bills were originally circulated by fringe anti-abortion groups in 2013, but the legislative push has picked up speed over the past year.

Many women do not know they are pregnant before six weeks — pregnancies are measured from the date of a woman’s last period, not the date of conception — making these laws a nearly complete ban on abortion in many cases. Ohio’s law includes an exception only if the mother’s life is threatened or she faces serious bodily harm from carrying the pregnancy to term.

Courts in Iowa, Kentucky, and North Dakota have blocked similar laws so far. Most anti-abortion politicians and activists are aware that these bills have no chance of becoming law in their state or surviving lower court review, but they’re pushing them in an effort to get the issue back before the Supreme Court. The ultimate goal is to convince the justices to overturn or greatly weaken Roe v. Wade, the 1973 Supreme Court decision that legalized abortion nationwide under the Fourteenth Amendment.

In the Ohio lawsuit, the ACLU quoted DeWine saying that he was signing the law in an effort to advocate for “reversal of existing legal precedents.”

Many abortion rights advocates, however, are confident that if the current Supreme Court takes up one of these cases, they would respect precedent and maintain the core of Roe v. Wade, keeping abortion legal nationwide.