A case being brought in the Colorado district court of Denver County is challenging the constitutionality of a controversial keyword search warrant and potentially curbing a law enforcement practice that has implications for the criminalization of abortion.

A reverse keyword search warrant is a surveillance technique that lets police start with a search term of interest and identify users who have searched it within a particular period. In concrete terms, that could mean identifying all the users who search for a specific name or address — or, in a scenario that has caused anxiety recently, everyone who searches for “abortion drugs.” Proponents of the technique say they’re an important tool for identifying criminals, but civil liberties groups see the warrants as a new and chilling threat to privacy.

Now, a legal challenge presents one of the first major tests of the constitutionality of those warrants. Attorney Mike Price, Fourth Amendment Center litigation director at the National Association of Criminal Defense Lawyers, is representing a defendant who was identified through the use of a keyword warrant — and arguing that all evidence derived from the warrant should be suppressed.

“Reverse keyword warrants are a new type of search,” Price writes in a motion to suppress evidence in the case. “They are unlike anything courts have approved in the past, and they are antithetical to both the Fourth Amendment and the Colorado Constitution.”

As reported by Forbes, the case involves a tragic incident from August 2020 in which a group of teenagers allegedly set fire to a Denver house, causing a deadly blaze that took the lives of five members of a Senegalese family, including two young girls.

While three suspects have now been identified, legal filings seek to challenge the use of evidence derived from keyword warrants, where police request that Google provide information on the accounts of users who have searched for certain terms.

According to coverage in The Denver Post, police initially struggled to identify the assailants in the case and turned to a range of surveillance techniques — many of which are controversial in their own right — to hone in on suspects.

First, a series of warrants served to cell phone providers produced a list of 7,000 mobile devices within a one-mile radius of the targeted house around the time it was set aflame. After eliminating devices commonly based in the area using a cell-site simulator (aka Stingray), they obtained location data connected to the remaining phones, focusing on those that matched the movements of a vehicle seen leaving the crime scene.

Separately, police asked Google for the details of any accounts that had searched for the address of the house in the two weeks before the fire and found three that could be linked to the location data, putting them at the scene of the crime. Through the combination of these surveillance methods, police were able to arrest three teenage suspects in January 2021 who have been charged with a wide range of crimes, including murder.

In an email statement, Google spokesperson Matt Bryant told The Verge:

“As with all law enforcement requests, we have a rigorous process that is designed to protect the privacy of our users, including by pushing back on overly broad requests, while supporting the important work of law enforcement.”

A motion to suppress

On June 30th, a new filing in the case was made by Price in his capacity as counsel for one of the defendants. The filing moves to suppress all evidence obtained from the keyword search warrant, arguing that it is a violation of constitutional rights.

Without the reverse keyword search, the motion argues, the defendant would not have been identified — so all evidence derived from that identification, including further searches of the suspect’s social media accounts and text messages, should be dismissed.

A search that encompasses the data of all Google users may be “one of the broadest searches in Fourth Amendment history,” the motion argues.

“No court has considered the legality of a reverse keyword search, but its constitutional defects are readily apparent and should have been obvious to all involved. It is a 21st century version of the general warrants that the Fourth Amendment was designed to guard against. Just as no warrant could authorize the search of every home in America, no warrant can compel a search of everyone’s Google queries.”

The motion to suppress also has the backing of the Electronic Frontier Foundation, which filed an amicus brief in support. In a blog post introducing the brief, EFF’s surveillance litigation director Jennifer Lynch and senior staff attorney Andrew Crocker argue that keyword warrants “are totally incompatible with constitutional protections for privacy and freedom of speech and expression,” casting a dragnet that theoretically encompasses the data of more than a billion Google users.

The authors also explicitly invoke privacy risks in a post-Roe America, arguing that the same techniques could be used to find abortion seekers. “Should the police be able to ask Google for the name of everyone who searched for the address of an abortion provider in a state where abortions are now illegal?” Lynch and Crocker write. “What about people who searched for gender-affirming healthcare providers in a state that has equated such care with child abuse?”

The EFF is far from alone in opposing keyword warrants. In 2020, a group of civil rights organizations led by the Surveillance Technology Oversight Project sent a letter to Google asking that the search giant provide greater transparency on how often law enforcement agencies requested data using keyword and geofence warrants.

“These blanket warrants circumvent constitutional checks on police surveillance, creating a virtual dragnet of our religious practices, political affiliations, sexual orientation, and more,” the letter reads. “As a leading recipient of geofence and keyword warrants, Google is uniquely situated to provide public oversight of these abusive practices.”

Update July 1st, 4:15PM ET: Updated to include comment from Google.