TOPEKA — Two Kansas doctors who have filed a lawsuit against a sweeping new state abortion law are attacking its form as well as its substance, hoping their objection to how lawmakers enacted the statute dooms it quickly.

But an anti-abortion leader sees the move as “desperate.”

Dr. Herbert Hodes and his daughter, Dr. Traci Nauser, who perform abortions at their health center in Overland Park, have asked a judge to strike down the entire law before their lawsuit goes to trial in Shawnee County District Court. In a filing late last month, they argued that the bill approved by legislators and signed by Gov. Sam Brownback contained more than one subject.

The Kansas Constitution declares that most legislative bills must contain only one subject. The new law bans sex-selection abortions, blocks tax breaks for providers and prohibits them from furnishing instructors or materials for public schools’ sexuality courses. The new restrictions affect providers’ websites and spell out what information patients must receive before their pregnancies are terminated.

Attorneys for Hodes and Nauser contend those provisions are far-ranging enough to qualify as multiple subjects. They also note that the bill also contains a section aimed at improving services for parents of children with Down syndrome or other conditions diagnosed during or after pregnancy.

District Judge Rebecca Crotty let most of the new law take effect last month, rather than blocking its enforcement while the lawsuit is pending. Stephanie Toti, an attorney for the New York-based Center for Reproductive Rights, which is representing Hodes and Nauser, said the issue of whether the bill has two subjects can be settled relatively quickly and should be dealt with first.

If the judge concludes the law has two subjects, Toti said, “Then there’s no sense in having years of protracted litigation.”

The state’s attorneys have yet to formally respond to the request from Hodes and Nauser to have the entire law struck down over the one-subject rule, and Crotty hasn’t scheduled a hearing on the request.

But in past court hearings and filings, the state’s lawyers have argued there are no grounds under the state or federal constitutions to strike it down. The legislation’s title was broad, beginning with a description of its contents as an act “concerning abortion.”

“We are aware of the latest court filing in this litigation and the State of Kansas will continue to defend the law as written,” Don Brown, a spokesman for Attorney General Derek Schmidt, said in a statement.

The state constitution says all bills must have only one subject, except for measures appropriating state funds and “bills for revision or codification of statutes.” Toti said the provision isn’t a technicality but a voter-ratified limit on legislative power to ensure Kansans can weigh in on disparate issues and advocate “nuanced positions.”

“Its purpose is to prevent the abuse of legislative power,” she said.

But the same provision of the state constitution says the one-subject rule will be applied liberally “to effectuate the acts of the legislature.”

Mary Kay Culp, executive director of Kansans for Life, the most influential anti-abortion group at the Statehouse, said the doctors’ attack on the law over the one-subject rule is “not legitimate.”

“It’s a desperate move by them to get a very reasonable bill that’s supported by a majority of people struck down,” Culp said.