Police are finding suspects based on their online searches as courts weigh privacy concerns

Police Use of “Reverse Keyword” Warrants Raises Privacy Concerns

Criminal investigators struggling with difficult cases have increasingly turned to Google for assistance, requesting what are known as “reverse keyword” warrants to identify potential suspects based on their search histories. This investigative technique, which works backward by identifying internet addresses where specific terms were searched, has sparked significant debate over privacy rights.

Unlike traditional search warrants targeting known suspects, these reverse warrants cast a wider net. Investigators request data from Google about everyone who searched for particular terms within a specified timeframe—such as an address where a crime occurred or phrases like “pipe bomb.”

The approach has proven effective in several high-profile cases. Police have successfully employed keyword warrants to investigate bombings in Texas, a political assassination in Brazil, and a deadly arson in Colorado. Investigators recognize that as Google’s search engine has become the primary gateway to the internet, people’s daily activities increasingly leave digital footprints that can provide valuable evidence.

A recent Pennsylvania Supreme Court decision has brought this investigative method into sharper focus. The court upheld the use of a reverse keyword warrant in a rape investigation that led to the conviction of John Edward Kurtz, a state prison guard. Police, having exhausted other leads, obtained a warrant directing Google to reveal accounts that had searched for the victim’s name or address during the week of the attack.

More than a year after the warrant was issued, Google reported that two searches for the victim’s address were made hours before the assault from a specific IP address. This information led investigators to Kurtz’s home. Subsequent surveillance and DNA testing confirmed his involvement, ultimately resulting in his confession to the rape and attacks on four other women over five years. Kurtz, now 51, received a sentence of 59 to 280 years.

While the Pennsylvania Supreme Court rejected Kurtz’s privacy claims, the justices were divided on their reasoning. Three justices held that Kurtz should not have expected his Google searches to remain private, while three others maintained that police had probable cause to seek information about anyone who had searched for the victim’s address before the attack. A dissenting justice argued that probable cause requires more than just a “bald hunch” or guessing that a perpetrator used Google.

Julia Skinner, a prosecutor in the Kurtz case, explained that reverse keyword searches are most effective when targeting specific and unusual terms, such as a distinctive name or address. “I don’t think they’re used super frequently, because what you need to target has to be so specific,” she noted.

In a similar Colorado case, authorities sought IP addresses for anyone who searched for the address of a home where a deadly arson occurred. The warrant returned information on 61 searches made by eight accounts, helping identify three teenage suspects. The Colorado Supreme Court ruled in 2023 that although the keyword warrant had constitutional defects, the evidence could be used because police had acted in good faith based on their understanding of the law at the time.

Privacy advocates, including the American Civil Liberties Union, have expressed serious concerns about this investigative approach. They argue it gives police “unfettered access to the thoughts, feelings, concerns and secrets of countless people.” Civil liberties groups contend that extending law enforcement powers to online keywords effectively turns every search user into a suspect.

Google, in response to questions about these warrants, stated: “Our processes for handling law enforcement requests are designed to protect users’ privacy while meeting our legal obligations. We review all legal demands for legal validity, and we push back against those that are overbroad or improper, including objecting to some entirely.”

It remains unclear exactly how many keyword warrants are issued annually, as Google does not categorize the warrants it receives by type. The Electronic Frontier Foundation and the Pennsylvania Association of Criminal Defense Lawyers noted this data gap in a recent legal brief.

These reverse keyword warrants differ from “geofence” warrants, which seek information about who was in a specific area at a particular time—a method whose constitutionality is currently under review by the U.S. Supreme Court.

For many individuals, Google search history contains deeply personal information about health issues, political beliefs, financial decisions, and spending patterns. University of Pennsylvania law professor David Rudovsky raised the question of how embarrassing it would be if every Google search “was now out there, gone viral.”

In his opinion on the Kurtz case, Pennsylvania Justice David Wecht distinguished between choosing to search for information on Google and the broad collection of cellphone location data that the U.S. Supreme Court limited in a 2018 decision. “A user who wants to keep such material private has options,” Wecht wrote. “That user does not have to click on Google.”

As this investigative technique continues to evolve, courts will likely face ongoing challenges balancing effective law enforcement with constitutional privacy protections in the digital age.