A North Dakota judge has issued a ruling striking down as unconstitutional a 2011 state law banning medical abortion.

The law was due to take effect in August 2011, but the Centre for Reproductive Rights filed a lawsuit on behalf of Red River Women's clinic, based in Fargo, arguing that the law unconstitutionally restricts abortion access for women.

In his ruling on Monday, which followed a three-day trial in April, which focused on the safety of the procedure, district court judge Wickham Corwin said that the state of North Dakota had failed to demonstrate any need to regulate medical abortion, "much less a compelling need".

He also described the "declared legislative purpose and the means selected to advance that purpose" as "contrived and pretexual".

His ruling will add to a growing list of successful court challenges that have been filed following a record number of state-legislated abortion restrictions across the US.

Corwin had already granted an injunction preventing the North Dakota law from taking effect.

Autumn Katz, the lead attorney for the CRR, said: "It won't have any effect on any other state laws or court case but it adds a growing list of court cases that are striking down totally unnecessary and restrictive laws. He has seen through the pretext for such laws as 'contextual and contrived'.

"The only reasons these laws are passed is to restrict women's access to abortion care."

In a 58-page judgment, Corwin concluded that the state had "no justification for regulation or restriction" on medical abortion.

He added: "Furthermore, even if some regulation was justifiable, the means selected by the legislature are both counterintuitive and counterproductive."

His ruling looked at the "stark" alternative to safe and legal abortion and cited World Health Organisation data on illegal abortions, which show that on a global basis, unsafe abortions kill 470,000 women a year. It contrasted unsafe, illegal abortions with medicated abortions performed by physicians in accordance with the type of "evidence-based protocol" followed by the Red Rover Women's clinic.

Corwin said medicated abortion under this type of protocol is an "extremely safe and effective procedure" where the risk of a "significant adverse effect" is so low it is difficult to quantify.

He concluded: "The amendments do nothing to promote women's health. They serve only to create insurmountable barriers that effectively eliminate medical abortions as an available option."

The state attorney general, Wayne Stenehjem, has said that the state will defend the law before the North Dakota Supreme Court.

A hearing is due shortly for a related challenge by the CRR on North Dakota's recently passed law requiring abortion clinics to have admitting privileges at a nearby hospital.

guardian.co.uk © Guardian News and Media 2013