April 16 (Reuters) - A federal judge on Wednesday permanently blocked North Dakota from enforcing the country's most restrictive abortion law, a ban on ending a pregnancy once a fetal heartbeat can be detected, as early as six weeks after conception.
North Dakota's only abortion clinic had challenged the law approved by the state legislature in 2013, and U.S. District Judge Daniel Hovland last July had temporarily blocked it from taking effect.
"The state of North Dakota has presented no reliable medical evidence to justify the passage of this troubling law," Hovland wrote in a 25-page opinion released on Wednesday.
Hovland said the U.S. Supreme Court has recognized the constitutional right of women to end a pregnancy before the fetus is determined to be viable for more than 40 years and the federal court is obligated to uphold that precedent.
The U.S. Supreme Court recently declined to hear an appeal of a ruling that struck down a 20-week abortion ban in Arizona and has never held that viability occurs at the point of conception, he said.
The North Dakota attorney general's office had no immediate comment on the ruling, a spokeswoman said.
Operators of the Red River Women's Clinic in Fargo had said the law would effectively ban nearly all abortions performed there, forcing it to close.
The clinic's closing would leave the closest alternate clinics about 250 miles (400 km) away in Minneapolis and St. Paul, Minnesota, or in Sioux Falls, South Dakota.
The North Dakota abortion ban approved in early 2013 was among a host of laws passed by Republican-led legislatures around the United States.
Arkansas lawmakers approved a law banning most abortions after 12 weeks of pregnancy, which was struck down in March by a federal judge as unconstitutional. The Arkansas attorney general has said he will appeal the ruling. (Reporting by David Bailey; Editing by Barbara Goldberg and Gunna Dickson)