A federal court blocked North Dakota's ban on abortion at about six weeks of pregnancy, the latest legal defeat for anti-abortion advocates.

The Wednesday ruling by the Eighth Circuit Court of Appeals permanently strikes down North Dakota's ban. The appeals court found that North Dakota's reasoning for the ban goes against Supreme Court precedent.

The state enacted the law in 2013 aiming to ban abortions at the point in the pregnancy when the unborn child possesses a heartbeat, according to the ruling.

However, the court said that it was bound by the Supreme Court's ruling in Roe v. Wade.

It was also bound by the ruling in Planned Parenthood v. Casey that found a state can restrict abortions only after the fetus can survive outside of the womb, a term called viability.

North Dakota argued that viability occurred when a heartbeat is detected, which is at about six weeks.

While the court said it was bound by the rulings in Roe and Casey, it added that the Supreme Court should evaluate the viability standard as medical technology has improved.

The pro-choice group Center for Reproductive Rights challenged the law in 2013 when it was passed.

The group was able to get it blocked temporarily later that year. It was also permanently blocked last year, with a federal judge saying that the Supreme Court doesn't permit a state to "terminate her pregnancy at a point prior to viability."

The center praised the decision, noting that it "reaffirms that the U.S. Constitution protects women from the legislative attacks of politicians who would deny them their right," said Nancy Northup, president of the pro-choice group Center for Reproductive Rights

The ruling is the center's second legal victory this year, having successfully fought and overturned an Arkansas ban on abortion services at 12 weeks.