Denver Police Encryption: When the Mile High City Went Dark

What Happened in Denver

Denver Police Department had operated with open radio communications for decades. Local news stations monitored police channels around the clock. Parents kept scanners during school emergencies. Neighborhood watch groups tracked nearby incidents. Amateur radio enthusiasts and scanner hobbyists formed an informal public safety network.

In late July 2019, that ended. After nearly a year of deliberation, Denver PD encrypted its radio system, making police radio traffic inaccessible to anyone without department-issued equipment. Aurora had already encrypted in 2016, and by 2022 the Colorado Freedom of Information Coalition counted more than two dozen agencies statewide that had encrypted all of their radio communications.

In 2021, Colorado responded by passing HB21-1250, which requires agencies that encrypt all their radio traffic to adopt policies for media access to primary dispatch channels. The law was meant to preserve transparency. In practice, the access policies have existed largely on paper.

The Marshall Fire: When Information Mattered Most

On December 30, 2021, the Marshall Fire tore through Boulder County, becoming Colorado's most destructive wildfire on record. Wind gusts up to 100 mph pushed flames across grasslands into suburban neighborhoods. Over 1,000 homes burned. More than 35,000 people evacuated, many with only minutes of warning.

Residents scrambled for information as official channels were overwhelmed. Evacuation zone boundaries shifted rapidly. Families who had been separated in the confusion had nowhere to turn for updates.

After-action reviews of the fire documented serious problems with emergency alerting: evacuation notices reached many residents late or not at all. That is exactly the gap scanner access has historically filled — letting residents hear what responders are doing before official alerts catch up.

The Marshall Fire primarily hit Boulder County, where police radio was still in the clear at the time, so residents who knew how could listen to the response directly. In Denver and Aurora, whose police radio was already encrypted, that kind of direct public window on a law enforcement response would not have existed — and since Boulder PD encrypted in October 2025, it no longer exists in Boulder either.

Impact on Local Journalism

Denver's local stations, KUSA 9News, KCNC CBS4, KDVR Fox31 among them, built their breaking news operations on scanner monitoring. Reporters dispatched within minutes of an incident. Photographers positioned themselves based on what they heard. Newsrooms could check police accounts against what was actually on the radio.

Before 2019, crime patterns across the city were visible to anyone listening. An independent record of police communications existed outside of what the department chose to announce. Since encryption, Denver news outlets depend far more heavily on what police choose to release. Significant incidents can go unreported for hours.

Denver did offer media outlets encrypted radios under a decryption license agreement — but with restrictions, including a ban on recording or broadcasting the transmissions, and journalists protested the arrangement when it took effect in 2019. HB21-1250 was supposed to standardize press access in 2021, yet a year after it passed, the Colorado Freedom of Information Coalition found Denver-area outlets were still blocked from listening.

A Decade-Long Slide Into Silence

Denver wasn't an isolated decision — it was the biggest domino in a statewide trend:

Boulder kept its communications open for decades — including through the Marshall Fire and the 2021 King Soopers shooting response — before encrypting in October 2025. None of the agencies that went dark produced public evidence that open radio had damaged officer safety or compromised investigations.

Meanwhile, Colorado State Patrol still dispatches in the clear across the state. If open radio were the safety hazard encrypting departments describe, the state's own highway patrol would not still be running it.

Colorado's Failed Promise: HB21-1250

In 2021, Colorado passed HB21-1250, a statewide law requiring law enforcement agencies that encrypt all of their radio traffic to establish media access policies. Journalists, civil liberties groups, and transparency advocates pushed hard for the provision.

The law requires:

• Written policies for credentialed media access to encrypted communications
• A process for journalists to apply for access
• Reasonable timeframes for reviewing applications

The result has been paperwork, not access. Agencies created policies, but actual access agreements are rare and often come with heavy strings attached — Aurora's, for example, requires news outlets to indemnify the department against claims arising from the agreement. The law has no meaningful enforcement mechanism.

A year after the law passed, the Colorado Freedom of Information Coalition reported that Denver-area news outlets were still blocked from listening to encrypted dispatch.

What You Can Do

Denver metro encryption is in place, but the policy is not settled:

• Contact your city council and push police departments to actually implement media access under HB21-1250, not just write a policy document
• Support local news organizations, which need resources to pursue access agreements and legal challenges
• Attend public meetings and raise transparency concerns when police budgets come up
• If you were harmed by the lack of real-time information during an emergency, write it down and share it with elected officials and advocacy groups
• Colorado State Patrol dispatch and some county agencies are still in the clear. Tell those officials you value that choice before it disappears too
• HB21-1250 lacks enforcement teeth. Advocate for amendments with real penalties for non-compliance