US state appeals against 'heartbeat' abortion law ruling
North Dakota has appealed against a US judge's ruling striking down the state's "foetal heartbeat" abortion ban, the strictest in the country.
State Attorney General Wayne Stenehjem has said more than one judge should have a chance to review the law.
The law bans abortions after a foetal heartbeat is detected, as early as six weeks into pregnancy.
In April, District Judge Daniel Hovland found the law "invalid and unconstitutional".
"The United States Supreme Court has spoken and has unequivocally said no state may deprive a woman of the choice to terminate her pregnancy at a point prior to viability," Judge Hovland wrote in his ruling.
The US Supreme Court ruled in the landmark Roe v Wade decision of 1973 that abortion must be legal until a foetus is viable, typically 22-24 weeks.
"The legislature passed the law in hopes that a higher court would revisit the issue," Mr Stenehjem said in a statement to the Associated Press news agency.
"It seems prudent that an appellate court should have an opportunity to consider the issue rather than have one judge overturn the judgment of the legislative assembly."
The case will now be heard by the US 8th Circuit Court of Appeals.
North Dakota's anti-abortion law was one of four such bills Republican Governor Jack Dalrymple signed into law in 2013.
The state's sole abortion clinic and the Center for Reproductive Rights sued to overturn the law and a US district judge ruled in April.
"The court was correct to call this law exactly what it is - a blatant violation of the constitutional guarantees afforded to all women," Center for Reproductive Rights president Nancy Northrup wrote in a statement after the April ruling.