PHOENIX (AP) — A day after lawmakers voted to put a border proposal on Arizona’s Nov. 5 ballot, a Latino advocacy group and a Democratic legislator filed a lawsuit challenging the measure because it contains an alleged constitutional defect.

In the challenge filed Wednesday, the group Living United for Change in Arizona and Democratic state Rep. Oscar De Los Santos alleged the proposal — which seeks to draw local police into immigration enforcement — violates a rule in the state constitution that says legislative proposals must cover a single subject.

If approved by voters, the proposal would make it a state crime for people to cross the Arizona-Mexico border anywhere except a port of entry, give state and local officers the power to arrest violators and let state judges order people to return to their home countries.

It also would make it a felony punishable by up to 10 years in prison for selling fentanyl that leads to a person’s death and require some government agencies to use a federal database to verify a noncitizen’s eligibility for benefits.

Jim Barton, a lawyer representing the advocacy group, expressed confidence that a court will block the measure from going on the ballot, saying he doesn’t believe a judge will see the measure — as its proponents do — as broadly applying to border issues.

Instead, Barton said the proposal deals with the unrelated subjects of immigration enforcement, the fentanyl crisis and the regulation of public benefits. “It’s defective — and every single person who’s involved in this knows that,” Barton said.

Republican leaders who supported the measure say those behind the lawsuit are trying to prevent Arizonans from voting on a top-priority issue.

“Arizonans have had enough and want change,” House Speaker Ben Toma, a Republican, said in a statement. In a separate statement, Senate President Warren Petersen, also a Republican, said he was confident the measure would survive court scrutiny and win approval from voters in November.

The office of Democratic Secretary of State Adrian Fontes, the state’s top elections officer who was the target of the lawsuit, declined to comment on the case.

It isn't the first time the Legislature has been accused of violating the single subject rule.

In late 2021, the Arizona Supreme Court upheld a lower-court ruling that concluded the Republican-controlled Legislature had violated the single subject rule when striking down a budget bill that was packed with a conservative wish list of unrelated policy items.

The Arizona proposal is similar to a Texas law that has been put on hold by a federal appeals court while it’s being challenged. A federal appeals court is currently considering Texas Gov. Greg Abbott’s appeal of the ruling that blocked enforcement of the state's law.

The Arizona Legislature's final approval of the border measure came on the same day that President Joe Biden unveiled plans to restrict the number of migrants seeking asylum at the U.S.-Mexico border.

Even though federal law already prohibits the unauthorized entry of migrants into the U.S., proponents of the measure say it’s needed because the federal government hasn’t done enough to stop people from crossing illegally over Arizona’s vast, porous border with Mexico. They also said some people who enter Arizona without authorization commit identity theft and take advantage of public benefits.

Opponents say the proposal would inevitably lead to racial profiling by police, saddle the state with new costs from law enforcement agencies that don’t have experience with immigration law and hurt Arizona’s reputation in the business world.

This isn’t the first time Republican lawmakers in Arizona have tried to criminalize migrants who aren’t authorized to be in the United States.

When passing its 2010 immigration bill, the Arizona Legislature considered expanding the state’s trespassing law to criminalize the presence of immigrants and impose criminal penalties. But the trespassing language was removed and replaced with a requirement that officers, while enforcing other laws, question people’s immigration status if they were believed to be in the country illegally.

The questioning requirement was ultimately upheld by the U.S. Supreme Court despite the racial profiling concerns of critics, but courts barred enforcement of other sections of the law.