The Supreme Court should recognize and give teeth to the critical, privacy-protecting limitations Congress placed on wiretaps, EFF told the court in an amicus brief we filed with the National Association of Criminal Defense Lawyers.

When law enforcement officials wiretap someone’s cell phone, the law doesn’t allow them to tap any phone they want anywhere in the country. The Wiretap Act (also known as “Title III” because it comes from Title III of the 1968 Omnibus Crime Control and Safe Street Act) permits wiretapping, but only under the narrowest of circumstances and subject to restrictive requirements carefully drawn to protect extremely sensitive privacy interests.

One of those requirements is that judges can only authorize wiretap orders for interceptions that occur within their districts. In other words, either the cell phone, the place of interception, or both, must be in the judge’s district for a wiretap to be valid under Title III. So an order issued by a judge whose district is comprised of a single state, say Kansas, can only authorize the interception of calls on a phone in Kansas or from an interception point in Kansas. In Dahda. v. U.S., a federal judge in Kansas issued a wiretap order allowing the defendants’ phones to be tapped anywhere in the country. This clearly runs counter to Title III’s geographic limitations.

There are strong policy reasons supporting these territorial limitations. A wiretap is a massive invasion of privacy because it allows the government to listen—in real-time—on our phone, text, and email conversations. Law enforcement can access any other information—like photos or documents—that we exchange during these conversations. When Congress legalized wiretapping, it sought to ensure that a wiretap is approved, monitored, and overseen by the judge with the closest nexus to the investigation, in consultation with prosecutors and investigators in charge of the case. Judges must closely supervise the use of wiretaps, making sure that they are still needed and are contributing useful information to prosecutors. The territorial limitations placed on wiretaps were designed to help judges keep a close watch on interceptions so they can ensure the intrusions into our private communications are as limited as possible.

Those privacy interests are even more acute when wiretaps are aimed at cell phones, which is almost always the case nowadays. (The law was amended in 1986 to extend its restrictions to electronic communications.) In 2016, over 43 million conversations were intercepted, 93% of which were from mobile devices. The amount of private information that can be gleaned from digital phones dwarfs the information that could be intercepted when wiretapping was first legalized. The devices we carry with us every day and keep at our bedsides contain intimate details of our private lives—our locations, our private texts and email, our conversations, photos, and videos. The vast majority of communications intercepted by wiretaps are non-incriminating.

Given these realities, the limitations and restrictions of Title III are even more important now than they were when the law was passed 50 years ago. Without territorial limitations on wiretaps, prosecutors could forum shop, seeking out courts that authorize the most wiretaps to get approval for their own.

Title III has a remedy for invalid wiretap orders: it specifies that evidence gathered from a deficient wiretap order can’t be used in court against the defendants. In Dahda v. U. S., we urged the Supreme Court to suppress, meaning throw out, the evidence gathered under wiretap orders that failed to meet the requirements of Title III.

We hope the Supreme Court sends a strong message to judges and prosecutors: wiretap orders that flout the territorial limitations established by Title III won’t be tolerated.