A federal judge granted a request Friday to temporarily block enforcement of a new Arkansas law that bans most abortions 12 weeks into a pregnancy.

U.S. District Judge Susan Webber Wright granted a motion for preliminary injunction in a lawsuit that the American Civil Liberties Union of Arkansas and the Center for Reproductive Rights brought on behalf of two Little Rock abortion providers.

The state's Republican-led Legislature enacted the 12-week abortion ban in March by overriding a veto from Democratic Gov. Mike Beebe.

Friday's decision means the ban, which was set to take effect in August, can't be enforced while the lawsuit is pending. A decision about the law's constitutionality is expected later.

The lawsuit says the ban is unconstitutional and clearly contradicts the U.S. Supreme Court's landmark Roe v. Wade decision, which legalized abortion until a fetus could viably survive outside the womb _ generally 22 to 24 weeks.

Arkansas' 12-week ban is tied to the date when a fetal heartbeat can typically be detected by an abdominal ultrasound. The measure includes exemptions for rape, incest, the life of the mother and highly lethal fetal disorders.

The lawsuit, which was filed on behalf of Dr. Louis Jerry Edwards and Dr. Tom Tvedten, names members of the Arkansas State Medical Board as defendants because the board is responsible for licensing medical professionals.

ACLU lawyer Bettina Brownstein said they were pleased with the ruling.

"I think it's likely that we'll succeed on the merit, that the statute will be declared unconstitutional and will never go into effect," Brownstein said.

Wright's decision comes days after she rejected Arkansas' attempt to have the lawsuit dismissed.

She ruled from the bench, "The court finds that the plaintiffs have established a threat of irreparable harm to themselves and to their patients."

The state has said the groups don't have standing to challenge the ban since it won't take effect until August. But Wright disagreed in an order earlier this week, saying the threat of enforcement was enough to challenge the law.