Reverse Keyword Search Warrants and the Threat to Online Privacy

Online privacy rights, already limited in the United States, face new threats from the advent of reverse keyword search warrants. In recent years, local and federal law enforcement have become increasingly reliant upon reverse keyword search warrants as an investigative digital dragnet tool to compel Google and other major search engine companies to furnish the personal information of users who have conducted a search query related to a crime. Known for their overbreadth and lack of precision, keyword warrants pull data on all users who have searched a set of keywords, including terms or phrases, during a set timeframe and, possibly, within a defined geographic area, and then work backward to investigate and identify potential leads or criminal suspects. Because these invasive dragnet requests are more than constitutionally suspect and can have serious implications for the civil rights and liberties of US internet users, they ought to be strictly regulated at the federal level.

It is necessary to acknowledge the natural tension caused by dueling privacy and public security concerns. More precisely, there are inherent limitations to a total ban, which may be considered impracticable and politically unpopular, particularly by law-enforcing entities that have become increasingly reliant upon such investigative techniques in today’s digital age.

However, short of a total statutory ban, there are alternative legislative fixes that can and should be implemented to regulate the use of reverse keyword search warrants and protect privacy and individual online activity to ensure that the law keeps pace with the advent of advanced technologies and all-permeating government surveillance of search histories. The following proposal calls upon federal and state legislatures to require technology companies to adopt comprehensive safeguards in their execution of keyword warrants to promote greater transparency and user privacy until such searches are outlawed.

This proposal starts from the position that reverse keyword search warrants are unconstitutional and reflects the support of multistate advocacy and legislative efforts to ban their use. Even if progress stalls at the federal level, swift action should be taken by state legislatures to prohibit government use of reverse search warrants to obtain keyword data of users under no individual suspicion of having committed a crime. States should model their legislation after New York’s approach, including measures such as the proposed Reverse Location & Reverse Keyword Search Prohibition Act.

Analysis

Reverse keyword warrants impose severe consequences on individual constitutional rights, which may range from breaching Fourth Amendment protections from unreasonable searches, to implicating innocent and unrelated users who search for similar relevant terms, to chilling First Amendment freedom of speech rights, and curtailing online access to critical healthcare information.

I. Keyword warrants threaten Fourth Amendment rights to be free from unreasonable government searches & risk implicating innocent users.

Reverse keyword warrants are especially threatening to the Fourth Amendment right to be free from unreasonable government searches because they can place hundreds or thousands of unsuspecting and innocent people in the crosshairs of law enforcement. By their nature, dragnet warrants request the disclosure of multiple users’ private information, where a search coincides with a certain set of keywords inputted into a search engine. This practice, which is based on a “mere hunch” that some unknown and unnamed individual may have queried a specific phrase related to a crime, runs directly counter to Fourth Amendment constitutional search requirements grounded in probable cause and particularity.

While documented keyword search warrants have, to date, been issued for narrower sets of search terms, such as the name of a victim or the location of a crime (e.g., site of arson attack), there is a heightened risk that, if left unchecked, such searches will only grow broader in scope and more demanding.

As a result, this practice—described by the Electronic Frontier Foundation as an “overbroad fishing expedition against unspecified targets”—can subject innocent users to unreasonable searches. It also risks erroneously implicating and dragging into major criminal investigations those individuals who search for similar keywords, especially where requested terms are not unique, and timeframes are imprecise.

II. Keyword warrants threaten chilling First Amendment rights to freedom of speech, and the judiciary is ill-equipped to guard against such violations.

In addition to curtailing Fourth Amendment rights, keyword warrants can have a particularly insidious effect on First Amendment freedom of speech. Specifically, such warrants have the potential to cause major anxiety amongst internet users who fear that their identities could be disclosed to the government because of the content of their search queries. In turn, these investigative practices risk chilling speech by leading users to refrain from conducting searches, especially where sensitive terms are involved.

Notwithstanding, the judiciary has failed to sufficiently guard against such infringements. In addressing the constitutionality of keyword warrants, recent cases, such as People v. Seymour (2023), have recognized a constitutionally protected privacy interest in users’ online search queries, finding that these queries directly impact individual free speech. However, here, the Colorado Supreme Court then failed to extend this protection. While the majority found that the Colorado state constitution protects users’ privacy interests in their search queries, it ultimately upheld the use of keyword warrants under the Fourth Amendment third-party doctrine, which does not recognize a reasonable expectation of privacy in information voluntarily provided to others. Further, the court’s shoddy deployment of the “good faith exception” allowed it to overlook the warrant’s “facial deficiency” without making a decisive ruling as to whether such warrants lacked probable cause.

The Seymour decision raises institutional competency concerns, signaling that courts have inconsistently applied constitutional requirements to keyword warrants—a subject that requires some level of technical expertise and know-how. In this case, the legislature may be better positioned to regulate this space, which is in dire need of enhanced privacy protections.

III. Keyword warrants threaten access to sensitive information, including abortion and reproductive health information

Search queries can reflect the most intimate and personal details of a user’s life, as they create an electronic record of “users’ most private and personal thoughts, opinions, and associations” connected to medical diagnoses and health conditions, religious beliefs, financial stability, sexual questions, and more. Because the search engine function has become a pervasive, modern, and necessary innovation belonging to everyday life (with Google Search reporting up to 100,000 queries per second), users often rely on search queries to secure answers to sensitive questions they may feel uncomfortable approaching a human confidant with, including friends, family, and doctors. If keyword warrants go unregulated, law enforcement will have “unfettered access to the thoughts, feelings, concerns, and secrets of countless people.”

In the healthcare context, studies show that 89% of US citizens search for health information online before seeking medical care. Naturally, as a result, reverse keyword warrants threaten access to abortion and reproductive healthcare information. Specifically, in the wake of Dobbs v. Jackson Women’s Health Organization (2022) and a post-Roe America, these warrants can be used as a “tool of oppression” by placing information-seeking individuals at risk of investigation and prosecution, particularly in states that have criminalized abortion.

Consequently, this phenomenon may lead users to abstain from searching for such information at all, thereby chilling speech. Even more troublingly, it could prevent people from receiving life-saving medical treatment, especially where medical studies show that internet searches are a major conduit for access to information on how to legally and safely obtain abortion medications.

Thus, strict regulation is needed to protect the interests of vulnerable populations, including those seeking abortion and reproductive health information, who are especially likely to be swept up in the crosshairs of dragnet keyword searches.

Recommendations

Regulating the execution of reverse keyword warrants by technology companies.

Beyond prohibiting government use of reverse search warrants, legislation should mandate that technology company search engines (e.g., Google, Bing, Microsoft, Yahoo!) implement stringent safeguards to better protect users’ personal information. Because technology companies are key players in the game, sustaining effective and lasting protection of American online privacy interests and constitutional civil rights and liberties requires accountability by all actors involved.

The following proposed legislative safeguards include establishing formal company policies and procedures that enact user notification requirements of requests by and disclosures made to law enforcement, strengthening data minimization policies by adopting auto-delete controls, and creating more avenues for anonymous browsing.

A. Strengthening transparency through user notification of requests by & disclosures to law enforcement

There is a need for increased transparency in requests received and disclosures made by technology companies. Generally, warrants and subpoenas issued to tech companies often contain a non-disclosure clause, preventing users from learning about when their search histories are shared with law enforcement.

Upon issuing a request for users’ search query data, there are two types of information sought by law enforcement: (1) records of search queries entered by a particular person, and (2) a list of the names, IP addresses, or other identifying information for some or all people who have entered a particular query into the search engine’s webpage.

The Electronic Frontier Foundation strongly supports user notification regarding government data requests as a core transparency and privacy-protective measure and publishes an annual “Who Has Your Back?” Report, which rates companies on such performance. Tech companies’ adoption of user notification procedures—similar to requirements under the Fair Credit Reporting Act (FCRA)—is paramount to the protection of 4th Amendment reasonable expectations of privacy in sensitive digital data, which ought to extend to individual search history and online activity stored by third-party service providers.

B. Data minimization policy: expanding the reach of auto-delete controls

Tech companies should be required to enact data minimization policies that incorporate the use of auto-delete controls to give users the choice to have search engines automatically and continuously delete their data. Companies should be required to follow in the footsteps of Google’s data retention policy, which makes auto-deletion the “default” for core activity settings and automatically and continuously deletes user Location History, search, voice, and YouTube activity data.

Auto-deletion is an especially salient feature because most users are unfamiliar with search engine privacy policies and are unaware of search history deletion capabilities, suggesting that users do not freely consent to providing search history information, but, rather, provide it “as part of a process to access an essential, everyday tool.” As such, even if auto-deletion becomes a default setting, companies should also be required to implement in-product notifications that regularly notify users about auto-delete controls to properly inform users of their privacy rights in online search history.

Furthermore, search engines, and especially Google, should be required to minimize the length of time they retain search history data to help mitigate privacy harms imposed by keyword warrants. Google currently retains this data for up to 18 months, which may amount to thousands or tens of thousands of searches. Minimizing the length of retention periods is important because it will help narrow the scope of data available to law enforcement serving reverse warrants.

C. Create new avenues for anonymous user browsing

Lastly, companies should be encouraged to provide avenues for anonymous browsing by permitting users to input a search query without it being logged into the search engine’s system or by allowing it to be immediately and permanently deleted after processing. The DOJ Criminal Division’s Computer Crime and Intellectual Property Section and the United States Attorneys’ Manual have acknowledged that when the government seeks URLs containing search queries, the request raises privacy concerns that deserve heightened consideration.

While Google Chrome has an “incognito” feature that claims to keep user activities private, such activity is, contrary to popular belief, not kept completely anonymous. Instead, search engines should follow the lead of privacy-protective browsers such as DuckDuckGo, which, by design, do not have search histories.

Even if an entirely anonymous search engine isn’t possible, technology companies should be required to, at a minimum, inform users of their right to access alternative anonymous browsing functions if they so choose.

Editor's note: DuckDuckGo, a company mentioned in this post, provided a charitable donation to Tech Policy Press in 2024.