WICHITA, Kan. (AP) — Kansas' law that restricts private health insurance coverage for abortions will go to trial to resolve whether it poses a substantial obstacle to women seeking to end pregnancies, a federal judge ruled Monday.

U.S. District Judge Julie Robinson rejected an argument by the American Civil Liberties Union of Kansas and Western Missouri that the 2011 law should be summarily invalidated because the Legislature's predominant purpose in passing the act was to impede access to abortion.

Instead, Robinson sided with the state in finding that the ACLU failed to provide any evidence about lawmakers' motivation. But, the judge said, a trial is necessary to determine the larger question of whether the significant costs for abortions many women must now pay for themselves create a substantial burden on the federal right to an abortion.

The state law prohibits private insurance companies from offering coverage for abortions in their general plans, except for when a woman's life is in danger. Kansas residents or employers who want abortion coverage must buy supplemental policies, known as riders.

Before the law's passage, companies comprising 70 percent of the insurance market share in Kansas included abortion coverage in comprehensive policies, the judge noted. Between July 2010 and July 2011, the three major health insurers paid claims for 137 abortions.

The cost for an abortion at a clinic ranges from $450 to $1,675, and hospital abortions can cost upwards of $10,000, Robinson said.

The ACLU contends that some women lack the finances to pay for an abortion out-of-pocket and are forced to delay the procedure while they save up for it. As the pregnancy advances, the cost of an abortion increases as do the medical risks.

"This increased cost to women seeking an abortion ... creates a genuine issue of material fact concerning the existence of an impact on women seeking an abortion in Kansas," Robinson wrote.

ACLU attorney Brigitte Amiri said Monday in an email that the group planned to "carefully read the decision, and then determine next steps."

The Kansas attorney general's office said in an emailed statement that it was "encouraged by the court's ruling and will continue to defend the state law."

A two-day trial is scheduled for March 18 in federal court in Topeka.