Law Enforcement, Courts Need to Better Understand IP Addresses, Stop Misuse

If police raided a home based only on an anonymous phone call claiming residents broke the law, it would be clearly unconstitutional.

Yet EFF has found that police and courts are regularly conducting and approving raids based on the similar type of unreliable digital evidence: Internet Protocol (IP) address information.

In a whitepaper released today, EFF challenges law enforcement and courts’ reliance on IP addresses, without more, to identify the location of crimes and the individuals responsible. While IP addresses can be a useful piece of an investigation, authorities need to properly evaluate the information, and more importantly, corroborate it, before IP address information can be used to support police raids, arrests, and other dangerous police operations.

IP address information was designed to route traffic on the Internet, not serve as an identifier for other purposes. As the paper explains, IP addresses information isn't the same as physical addresses or license plates that can pinpoint an exact location or identify a particular person. Put simply: there is no uniform way to systematically map physical locations based on IP addresses or create a phone book to lookup users of particular IP addresses.

Law enforcement’s over-reliance on the technology is a product of police and courts not understanding the limitations of both IP addresses and the tools used to link the IP address with a person or a physical location. And the police too often compound that problem by relying on metaphors in warrant applications that liken IP addresses to physical addresses or license plates, signaling far more confidence in the information than it merits.

Recent events demonstrate the problem: A story in Fusion documents how residents of a farm in the geographic center of America are subjected to countless police raids and criminal suspicion, even though they’ve done nothing wrong. A story in Seattle’s newspaper The Stranger described how police raided the home and computers of a Seattle privacy activist operating a Tor exit relay because they mistakenly believed the home contained child pornography. And these are just two stories that found their way into the media.

These ill-informed raids jeopardize public safety and violate individuals’ privacy rights. They also waste police time and resources chasing people who are innocent of the crimes being investigated.

The whitepaper calls on police and courts to recalibrate their assumptions about IP address information, especially when it is used to identify a particular location to be searched or individual to be arrested. EFF suggests that IP address information be treated, in the words of the Supreme Court, as more like “casual rumor circulating in the underworld,” or an unreliable informant. The Constitution requires further investigation and corroboration of rumors and anonymous tips before police can rely upon them to establish probable cause authorizing warrants to search homes or arrest individuals. The same should be true of IP address information.

The paper also explains why the technology’s limitations can make it unreliable and how the Supreme Court’s rules around unreliable information provided by anonymous informants should apply to IP address information in warrant applications. The paper concludes with two lists of questions to ask and concrete steps to take: one for police and one for judges. The goal is to better protect the public so that the misuse of IP address information doesn’t lead to a miscarriage of justice.

We hope the whitepaper can serve as a resource for law enforcement and courts while also triggering a broader conversation about IP address information’s use in criminal investigations. In the coming months, EFF hopes to discuss these concerns with law enforcement and courts with the goal of preventing unwarranted privacy invasions and violations of the Fourth Amendment. We also hope that our discussions will result in better law enforcement investigations that do not waste scarce police resources. If you are a law enforcement agency or court interested in this issue, please contact info@eff.org.