Last week, EFF, along with the Criminal Defense Attorneys of Michigan, ACLU, and ACLU of Michigan, filed an amicus brief in People v. Carson in the Supreme Court of Michigan, challenging the constitutionality of the search warrant of Mr. Carson's smart phone.

In this case, Mr. Carson was arrested for stealing money from his neighbor's safe with a co-conspirator. A few months later, law enforcement applied for a search warrant for Mr. Carson's cell phone. The search warrant enumerated the claims that formed the basis for Mr. Carson's arrest, but the only mention of a cell phone was a law enforcement officer's general assertion that phones are communication devices often used in the commission of crimes. A warrant was issued which allowed the search of the entirety of Mr. Carson's smart phone, with no temporal or category limits on the data to be searched. Evidence found on the phone was then used to convict Mr. Carson.

On appeal, the Court of Appeals made a number of rulings in favor of Mr. Carson, including that evidence from the phone should not have been admitted because the search warrant lacked particularity and was unconstitutional. The government's appeal to the Michigan Supreme Court was accepted and we filed an amicus brief.

In our brief, we argued that the warrant was constitutionally deficient and overbroad, because there was no probable cause for searching the cell phone and that the warrant was insufficiently particular because it failed to limit the search to within a time frame or certain categories of information.

As the U.S. Supreme Court recognized in Riley v. California, electronic devices such as smart phones “differ in both a quantitative and a qualitative sense” from other objects. The devices contain immense storage capacities and are filled with sensitive and revealing data, including apps for everything from banking to therapy to religious practices to personal health. As the refrain goes, whatever the need, “there's an app for that.” This special nature of digital devices requires courts to review warrants to search digital devices with heightened attention to the Fourth Amendment’s probable cause and particularity requirements.

In this case, the warrant fell far short. In order for there to be probable cause to search an item, the warrant application must establish a “nexus” between the incident being investigated and the place to be searched. But the application in this case gave no reason why evidence of the theft would be found on Mr. Carson's phone. Instead, it only stated the allegations leading to Mr. Carson's arrest and boilerplate language about cell phone use among criminals. While those facts may establish probable cause to arrest Mr. Carson, they did not establish probable cause to search Mr. Carson's phone. If it were otherwise, the government would always be able to search the cell phone of someone they had probable cause to arrest, thereby eradicating the independent determination of whether probable cause exists to search something. Without a nexus between the crime and Mr. Carson’s phone, there was no probable cause.

Moreover, the warrant allowed for the search of “any and all data” contained on the cell phone, with no limits whatsoever. This type of "all content" warrants are the exact type of general warrants against which the Fourth Amendment and its state corollaries were meant to protect. Cell phone search warrants that have been upheld have contained temporal constraints and a limit to the categories of data to be searched. Neither limitations—or any other limitations—were in the issued search warrant. The police should have used date limitations in applying for the search warrant, as they do in their warrant applications for other searches in the same investigation. Additionally, the warrant allowed the search of all the information on the phone, the vast majority of which did not—and could not—contain evidence related to the investigation.

As smart phones become more capacious and entail more functions, it is imperative that courts adhere to the narrow construction of warrants for the search of electronic devices to support the basic purpose of the Fourth Amendment to safeguard the privacy and security of individuals against arbitrary invasions by governmental officials.