A coalition of advocacy groups and several district attorneys rallied outside the Colorado Capitol on Thursday to oppose a ballot measure that, if approved by voters in November, would require state and local law enforcement to cooperate with federal immigration authorities.

Backed by Advance Colorado, Proposition 81 would require local law enforcement agencies to notify Immigration and Customs Enforcement when they charge a person who is in the country illegally with a violent crime or when the individual has previously been charged with a felony. This also applies when the person’s legal status cannot be determined.

Kristi Burton Brown, executive vice president of Advance Colorado, told Colorado Politics that the group is pursuing the measure because state law now bars law enforcement from proactively reporting violent offenders or repeat felons to the U.S. Department of Homeland Security.

She said that, under a recent state law, an officer faces a fine of up to $50,000 for choosing to report a violent offender to federal authorities. She also noted that other “sanctuary” states, including California and New York, include exceptions in these situations that Colorado does not.

While many have characterized Colorado as a “sanctuary state,” Gov. Jared Polis has pushed back on the label, saying the state “fully cooperates with federal authorities in identifying, apprehending and prosecuting criminals – regardless of immigration status.”

Over the years, Colorado has adopted several laws whose provisions fall under the broad outlines of what constitutes a “sanctuary” state.

Notably, a 2019 law prohibits a law enforcement officer from arresting or detaining an individual solely based on a civil immigration detainer and bars a probation officer or probation department employee from providing an individual’s personal information to federal immigration authorities.

A 2021 law blocks employees from providing personally identifiable information to immigration enforcement without a warrant or as part of a criminal investigation. In 2025, Colorado’s legislators imposed the same restrictions on local government employees as well as judicial and legislative employees.

Some local governments, such as Denver, have also adopted “sanctuary” policies.

Speaking from the Capitol steps Thursday, ACLU Colorado director Olivia Mendoza said approving Proposition 81 would make communities less safe, particularly under the current administration.

“We have seen that since the beginning of the Trump administration’s second term, our communities have been gripped by the fear of ICE’s brutal immigration enforcement, from warrantless arrests to physical brutality to deplorable detention conditions,” she said. “ICE has no place in our state, and Amendment 81 invites them to take a strong foothold in Colorado.”

Mendoza argued that Proposition 81 violates the Due Process Clause of the U.S. Constitution, which prohibits the government from taking away an individual’s life, liberty or property without fair legal proceedings.

Burton Brown countered that the allegations that the measure violates due process are unfounded because law enforcement would be allowed to report to ICE only after obtaining enough evidence to charge someone with a crime.

If the measure passed, it would require law enforcement to contact ICE every time they charge someone who has a prior criminal record, unless that person happened to have proof of citizenship with them in the form of a birth certificate or passport, according to Denver District Attorney John Walsh.

Walsh called Proposition 81 a “recipe for abuse,” saying it would inevitably lead to racial profiling and the detainment of citizens and legal residents.

“To make things much worse, this obligation triggers on charging a person with a crime, not on a conviction,” he added.

Burton Brown disagreed, noting that nothing in Proposition 81 allows profiling or gives ICE agents any authority they don’t have in Colorado.

She added, “Instead, this gives Colorado law enforcement the ability to report violent criminals or repeat felons if they are here illegally without facing a $50,000 fine from the state.”

Walsh insisted that Proposition 81 would further erode the already strained relationship between immigrant communities and law enforcement.

“Today, state and local law enforcement in this state can truthfully tell the victims and witnesses to a crime that we do not participate in federal civil immigration enforcement,” he said. “If Proposition 81 passes, we would no longer be able to do that.”

Larimer and Jackson County District Attorney Gordon McLaughlin also attended the rally.