The decision from U.S. District Judge B. Lynn Winmill was handed down Wednesday as part of a ruling that also overturns other abortion restrictions in Idaho.
The ruling is binding only in Idaho but could have a persuasive effect in lawsuits challenging similar bans in other states such as Arizona, where a suit is pending before the 9th U.S. Circuit Court of Appeals.
Ten states in all have enacted fetal pain laws since 2010, said Elizabeth Nash, a policy analyst with the Guttmacher Institute, which supports abortion rights and tracks laws affecting women's health.
Nebraska was first, followed over the next few years by Alabama, Arkansas, Arizona, Georgia, Idaho, Indiana, Kansas, Louisiana and Oklahoma.
But only three states have had the laws legally challenged. Eastern Idaho resident Jennie Linn McCormack was the first to sue over the fetal pain law and other abortion restrictions after Bannock County Prosecutor Mark Hiedeman charged her with a felony because police said she obtained an illegal abortion. A lawsuit has been brought in Georgia, as well; that case is still pending in the state courts.
Idaho Sen. Chuck Winder, who led the legislative push for the fetal pain law two years ago, said he and others would need to closely study Winmill's ruling before deciding how the state should proceed.
"I'm very disappointed in the court in its decision to overturn the right to protect a life and protect a life from the pain of abortion," the Boise Republican said.
McCormack's attorney, Richard Hearn of Pocatello, said Winmill's ruling makes it clear that any attempts by states to ban abortions before a fetus can survive outside the womb are unconstitutional.
The ruling cited two landmark U.S. Supreme Court cases Roe vs. Wade and Planned Parenthood vs. Casey to show a woman has an absolute right to an abortion before the point of viability, Hearn said.
"It's not just the fetal pain laws. It's that fetal heartbeat law in Arkansas, too," Hearn said. Picking a "pre-viability" date to ban abortions is unconstitutional, he said.
"It's as though legislatures all across the country are saying, 'We don't really care. We're just going to do it anyway in the face of the Constitution,'" Hearn said. "Thankfully Winmill put a stop to that in Idaho."
Officials with the National Right to Life Committee didn't return phone messages left by The Associated Press. And calls to the cellphone of David Ripley, the leader of Idaho Chooses Life, were unanswered.
Julie Rikelman, litigation director for the Center for Reproductive Rights, said her organization applauded Winmill's decision.
"For 40 years, the Supreme Court has consistently held that women's right to make their own decisions about whether to continue or end a pregnancy is guaranteed by the U.S. Constitution," she said in a statement. "Today's ruling has overturned a legislative assault by politicians who seek to interfere with that decision and deny women this fundamental right."