The Colorado Supreme Court agreed on Monday that a Park County judge excluded evidence from a drunk driving prosecution based on an incorrect belief that law enforcement lacked reasonable suspicion of a crime.

Dave A. Dacus stands accused of felony driving under the influence. He came to the attention of authorities after another motorist, giving only her first name, called in a tip alleging erratic driving. A sheriff’s deputy subsequently observed Dacus’ vehicle driving slowly, but otherwise normally, and approached him after Dacus pulled over to let other cars pass.

The deputy arrested Dacus after seeing multiple signs of intoxication.

Dacus argued the evidence from the traffic stop must be barred from his trial because the anonymous tip and the lack of corroboration from the deputy failed to create the reasonable suspicion needed to investigate him. A trial judge agreed with Dacus and ordered the evidence excluded.

However, the Supreme Court saw things differently. 

“Tips from identified citizen informants can alone provide a basis for finding reasonable suspicion to justify an investigatory stop,” wrote Justice Richard L. Gabriel in the June 24 opinion. The caller who reported Dacus “was a concerned citizen who was not likely to be fabricating the information that she was reporting.”

In reaching their conclusion, the justices looked to a highly similar decision from the U.S. Supreme Court that upheld — by 5-4 — law enforcement’s reliance on anonymous tips of dangerous driving, even if responding officers do not corroborate the behavior themselves.

Park County dispatchers received a call on Aug. 9, 2023 alleging a man in a distinctive-looking Jeep was weaving across lanes. The caller only identified herself as “Christina” and gave her location on the highway, but the dispatch system also captured her phone number and location. The call dropped because of bad cellular service.

The details of the call were transmitted to Deputy Joseph Sackett, who soon encountered a group of cars traveling behind the suspected Jeep. Sackett used his radar to estimate the Jeep was going 37 mph in a 50 mph zone, which he deemed unusual. He did not witness any swerving.

After the Jeep pulled over to let the other cars pass, Sackett parked behind it, activated his lights and approached the vehicle. Sackett contacted Dacus and allegedly saw and smelled signs of alcohol and marijuana in the Jeep. Dacus appeared under the influence and declined to take a chemical test. Sackett then arrested Dacus.

At a hearing in December, District Court Judge Amanda Hunter concluded the facts available to Sackett did not create reasonable suspicion to investigate Dacus. She believed the information about the tipster — the name “Christina” and a phone number — was insufficient to establish the caller’s reliability as a source.

“So, there would need to be some corroboration by law enforcement of the tip, the contents of the tip, to rely upon it,” Hunter said. Instead, “I have an anonyous tip with corroboration of only slow driving. And that’s not enough.”

The prosecution immediately appealed to the state Supreme Court, arguing there was no violation of the Fourth Amendment’s prohibition on unreasonable searches and seizures. 

“The totality of circumstances justified an investigatory stop in this case because Christina’s information indicated a minimal level of objective suspicion that the person to be stopped is committing, has committed, or is about to commit a crime of reckless driving or DUI,” argued Deputy District Attorney Stephanie Miller.

The Supreme Court pointed to a 2014 U.S. Supreme Court decision, Navarette v. California, calling it “substantially” similar. There, an anonymous caller informed dispatch a vehicle had run her off the road. Law enforcement located the truck, drove behind it for five minutes and saw nothing abnormal. Officers decided to pull the truck over and, smelling marijuana, searched the vehicle, uncovering 30 pounds of marijuana.

The court’s majority, deeming it a “close case,” upheld the use of the anonymous tip as grounds for reasonable suspicion. Justice Antonin Scalia, writing for the four dissenting members, argued the ruling amounted to a “freedom-destroying cocktail” allowing for police to stop drivers on the most minimal of uncorroborated accusations.

“After today’s opinion all of us on the road, and not just drug dealers, are at risk of having our freedom of movement curtailed on suspicion of drunkenness, based upon a phone tip, true or false, of a single instance of careless driving,” he wrote.

Colorado’s Supreme Court, however, applied the majority’s reasoning to conclude Christina’s tip was sufficiently reliable to investigate Dacus.

“To the contrary, the record established that she was an identified citizen informant and an unaffiliated bystander who was reporting criminal activity that she was observing in real time,” Gabriel explained. “For this reason alone, we conclude that reasonable suspicion existed to justify an investigatory stop of Dacus’s Jeep.”

The case is People v. Dacus.