A proposed ban on abortion after 20 weeks in Albuquerque, New Mexico, would be “unconstitutional and unenforceable,” the state’s attorney general said Wednesday in a letter to a city council member.

Attorney General Gary King, a Democrat, said that “recent federal court actions have struck down ordinances identical or similar to the proposed measure in Albuquerque,” citing a Tenth Circuit Court of Appeals decision that struck down a comparable ban on abortions in Utah, “because it unconstitutionally established viability at 20 weeks.”

Anti-choice activists began campaigning against abortion in the city three years ago, when nationwide anti-choice group Operation Rescue sent two “missionaries” there to garner support for a city petition. The group did gather the more than 12,000 signatures required to push a proposed 20-week abortion ban to a city-wide vote, scheduled to take place November 19.

A ban on abortion after 20 weeks in the city could significantly affect patients at Albuquerque’s Southwestern Women’s Options clinic, one of the few abortion providers in the United States that performs later abortions.

The American Civil Liberties Union of New Mexico has said it intends to pursue litigation against the ban if it is passed after the November vote.

In a press release, King said, “Voters have the right to know and decide whether they want to bear the protracted expense of litigation over a measure that is unconstitutional and unenforceable.”