“Key search warrants” – how the U.S. police can now use your search history to make you a suspect

When investigators hit a dead end, some are turning to an increasingly controversial digital tool: asking Google to identify who searched for certain words.

Known as reverse keyword warrants — sometimes referred to as “key search” warrants — the tactic flips the traditional logic of criminal investigations. Instead of starting with a suspect and building a case, police begin with a search term and work backward to find potential suspects.

How reverse keyword warrants work

In a traditional warrant, law enforcement targets a known individual, device, or address. With a reverse keyword warrant, investigators request data from Google about accounts or IP addresses that searched for specific terms within a defined time window.

That could mean anyone who searched for a victim’s home address, a person’s name, or phrases like “pipe bomb” before an attack.

Police have used the method in cases ranging from the 2018 Austin bombings to a deadly arson in Colorado and a rape investigation in Pennsylvania.

The appeal for investigators is obvious: Google’s search engine functions as a gateway to daily life, and many crimes leave digital traces before they occur.

A case that reached a state supreme court

In Pennsylvania, state police used a reverse keyword warrant after a 2016 rape investigation stalled. With no suspect, investigators obtained a warrant directing Google to disclose accounts that searched for the victim’s name or address during the week of the assault.

Google identified two searches made hours before the attack from a specific IP address. That lead eventually pointed to John Edward Kurtz, a former prison guard, who later confessed and was sentenced to decades in prison.

His lawyers argued that the warrant lacked probable cause and violated the Fourth Amendment’s protection against overly broad searches. The Pennsylvania Supreme Court ultimately upheld the warrant, though the justices were divided on their reasoning.

Some concluded that users do not have a strong expectation of privacy in search queries shared with a third party like Google.

Others said police had sufficient probable cause under the circumstances. A dissenting justice warned that investigators relied on little more than a “bald hunch” that a perpetrator would have used Google.

A broader constitutional debate

Civil liberties advocates argue that reverse keyword warrants invert the traditional standard of probable cause by casting a wide net first and narrowing suspects later.

In court filings, privacy groups warned that the practice risks exposing “the thoughts, feelings, concerns and secrets” of countless innocent people whose only connection to a crime is a search query.

Google says it reviews law enforcement demands for legal validity and pushes back against requests it considers overbroad or improper. The company does not publicly break down how many keyword warrants it receives each year.

Supreme Court rules on related issues

Courts in different states have taken varied approaches. In Colorado, the state’s supreme court found a keyword warrant constitutionally defective for lacking individualized probable cause but allowed the evidence under a “good faith” exception.

Meanwhile, the U.S. Supreme Court is set to rule on the constitutionality of related “geofence” warrants, which seek data on devices in a specific location at a specific time. That decision could influence how courts view reverse keyword searches in the future.

As digital footprints become increasingly detailed, the legal system is being forced to answer a fundamental question: when your search history can make you a suspect, where does the Fourth Amendment draw the line?

Sources: The Associated Press, Pennsylvania Supreme Court opinion, Colorado Supreme Court opinion, American Civil Liberties Union brief, Google statement

This article is made and published by Asger Risom, who may have used AI in the preparation