PIERRE, S.D. – Gov. Mike Rounds signed legislation Monday banning nearly all abortions in South Dakota, setting up a court fight aimed at challenging the 1973 U.S. Supreme Court decision that legalized abortion.

The bill would make it a crime for doctors to perform an abortion unless the procedure was necessary to save the woman’s life. It would make no exception for cases of rape or incest.

Planned Parenthood, which operates the state’s only abortion clinic, in Sioux Falls, has pledged to challenge the measure.

Rounds issued a written statement saying he expects the law will be tied up in court for years and will not take effect unless the U.S. Supreme Court upholds it.

“In the history of the world, the true test of a civilization is how well people treat the most vulnerable and most helpless in their society. The sponsors and supporters of this bill believe that abortion is wrong because unborn children are the most vulnerable and most helpless persons in our society. I agree with them,” Rounds said in the statement.

The governor declined all media requests for interviews Monday.

The Legislature passed the bill last month after supporters argued that the recent appointments of conservative justices John Roberts and Samuel Alito have made the U.S. Supreme Court more likely to overturn Roe v. Wade.

Abortion opponents already are offering money to help the state pay legal bills for the anticipated court challenge, Rounds has said.

Lawmakers said an anonymous donor has pledged $1 million to defend the ban, and the Legislature set up a special account to accept donations for legal fees.

Under the new law, to go into effect July 1, doctors could get up to five years in prison for performing an illegal abortion.

Rounds noted that it was written to make sure existing restrictions would still be enforced during the legal battle.

Current state law sets increasingly stringent restrictions on abortions as pregnancy progresses; after the 24th week, the procedure is allowed only to protect the woman’s health and safety.

Kate Looby, state director of Planned Parenthood, said the organization has not yet decided whether to challenge the measure in court or to seek a statewide public vote in November. A referendum would either repeal the abortion ban or delay a court challenge to the legislation.

“Obviously, we’re very disappointed that Governor Rounds has sided on the side of politics rather than on the side of the women of South Dakota to protect their health and safety,” Looby said.

She said Planned Parenthood would continue providing services that include family planning, emergency contraception and safe and legal abortions.

About 800 abortions are performed each year in the state.