As Americans have adopted new technologies to make life more efficient, the government has devised new ways to use that technology to curtail the Fourth Amendment. If you care about your digital privacy, you need to know about this Supreme Court case: Carpenter vs. United States and the question of how easily the government gets to track you.

The Trump administration says the government has the right to track your cellphone’s every movement, asserting that Americans have no right to privacy in the records they convey to third parties, the New York Times reports.

But that claim is clearly inconsistent with contemporary technological developments—your cellphone is constantly shedding information that goes right to third parties, whether you want it to or not. And if the justices accept this flimsy argument, they will allow the government to create a dangerous new rule that subverts constitutional limitation on surveillance.

It’s becoming increasingly common for prosecutors to seek this kind of phone evidence from tech companies. But this legal challenge could have huge implications for everybody’s privacy in the digital age.

As noted by the Times: “The court’s decision, expected by June, will apply the Fourth Amendment, drafted in the 18th century, to a world in which people’s movements are continuously recorded by devices in their cars, pockets and purses, by toll plazas and by transit systems. The court’s reasoning may also apply to email and text messages, internet searches, and bank and credit card records.”

On the one hand, the government argues that “you have agreed to the carrier’s terms of service when you sign up for your phone. You know they can track your location. Therefore, you have no reasonable expectation of privacy. You have voluntarily turned over your data to the phone company, which is a third party. Therefore, the police needn’t get a warrant to ask for this information.” You can see the legal logic here.

On the other hand: Really? No reasonable expectation of privacy whatsoever? Everybody knows their smartphone can track their location, but few of us take the time to consider the full and deep consequences of that fact—including that the police might use your phone records to determine everywhere you’ve been over the span of months or years. The implication seems to be that users are a bunch of dummies for agreeing to the phone company’s litany of legalese. Never mind that the alternative is to live without a smartphone, which is increasingly difficult if not impossible for many people who want to live and work in the 21st century.

The Supreme Court has generally indicated that the government cannot use these technologies to shrink our rights. In the age of originalism, this approach frequently requires an 18th-century solution to a 21th-century problem. The court has held, for instance, that the use of a thermal-imaging device on a home is similar to a physical intrusion in 1791, and the placement of a GPS device on a car is analogous to a founding-era trespass.

But the government insists that anybody who wants to carry around a cellphone—so, almost everyone—must accept the reality that law enforcement can track your movements without a warrant based on probable cause.

The government’s argument raises a chilling possibility: If Congress repealed the SCA tomorrow, law enforcement could access every American’s cell site info in a snap. The courts could place no meaningful limits on the resulting dragnet, because the government’s search of our every movement poses no Fourth Amendment concerns. ShareTweet