Imagine this: the government, for reasons you don't know, thinks you're a spy. You go on vacation and, while you're away, government agents secretly enter your home, search it, make copies of all your electronic devices, and leave. Those agents then turn those devices upside down, looking through decades worth of your files, photos, and online activity saved on your devices. They don't find any evidence that you're a spy, but they find something else—evidence of another, totally unrelated crime. You're arrested, charged, and ultimately convicted, yet you're never allowed to see what prompted the agents to think you were a spy in the first place.

Sounds like something from dystopian fiction, right? Yet it's exactly what happened to Keith Gartenlaub. In January 2014, the FBI secretly entered Gartenlaub's home while he and his wife were on vacation in China. Agents scoured the home, taking pictures, searching through boxes and books, and—critically—making wholesale copies of his hard drives.

Agents were authorized by the secret Foreign Intelligence Surveillance Court ("FISC") to search for evidence that Gartenlaub was spying for the Chinese government. There’s only one problem with that theory: the government has never publicly produced any evidence to support it. Nevertheless, Gartenlaub now sits in jail. Not for spying, but because the FBI’s forensic search of his hard drives turned up roughly 100 files containing child pornography, buried among thousands of other files, saved on an external hard drive.

Gartenlaub was tried and convicted, and he appealed his conviction to the Ninth Circuit Court of Appeals. EFF (along with our friends at the ACLU) recently filed an amicus brief in support of his appeal.

There are plenty of troubling aspects to Gartenlaub’s prosecution and conviction. For one, and unlike normal criminal prosecutions, neither Gartenlaub nor his lawyers have ever seen the affidavit and order issued by the FISC that authorized the search of his home. There are also legitimate concerns about the sufficiency of the evidence used to convict him.

But we got involved for a different reason: to weigh in on the Fourth Amendment implications of the FBI’s searches of Gartenlaub’s electronic devices. The unusual facts of this case gave us an unusually good opportunity to push for greater Fourth Amendment protections in all searches of electronic devices.

Here’s why: when agents copied and searched Gartenlaub’s devices, they were only authorized to search for national security-related information. But the prosecution that resulted from those searches and seizures had nothing to do with national security at all. So, either the FBI seized information that was outside of the warrant (which the Fourth Amendment prohibits); or it was relying on an exception to the warrant requirement, like “plain view”—an exception that allows law enforcement to seize immediately obvious contraband when the government is in a place to lawfully observe it.

Plain view makes sense in the physical world. If cops are executing a search warrant for a home to search for drugs, they shouldn’t have to ignore the dead body lying in the living room. But the way plain view works in the digital context—especially forensic computer searches—is not at all clear. How far can cops rummage around our computers for the evidence they’re authorized to look for? Does a warrant to search for evidence of drug dealing allow cops to open all the photos stored on our computer? Does an order authorizing a search for national security information let the government rifle through a digital porn collection? And where do we draw the line between a specific search, based on probable cause for specific information stored on a computer—which the Fourth Amendment allows— and a general search for evidence of criminal activity—which the Fourth Amendment prohibits?

Our electronic devices contain decades' worth of personal information about us. And, in many ways, searches of our electronic devices can be more intrusive than searches of our homes: there is information stored on our phones, computers, and hard drives, about our interests, our political thoughts, our sexual orientations, or religious beliefs, that might never have been previously stored in our homes—or, for that matter, anywhere at all. Because of the sensitivity of this data, we need clear restrictions on law enforcement searches of our electronic devices, so that every search doesn't turn into the type of general rummaging the Fourth Amendment was designed to prevent.

In our brief, we argued this case gave the Court a perfect opportunity to set a clear rule. We argued that the FBI’s search of Gartenlaub’s hard drives for evidence of regular, domestic crimes violated the Fourth Amendment, and we urged the Court to adopt a rule that would prohibit the FBI from using evidence that it obtained that was outside the scope of the initial search authorization. This would be a promising first step in limiting law enforcement’s electronic search powers and in protecting our right to privacy in the digital age.