This post was written by EFF legal intern Danya Hajjaji.

Law enforcement should be required to obtain a warrant to search data contained in abandoned cell phones, EFF and others explained in a friend-of-the-court brief to the Ninth Circuit Court of Appeals.

The case, United States v. Hunt, involves law enforcement’s seizure and search of an iPhone the defendant left behind after being shot and taken to the hospital. The district court held that the iPhone’s physical abandonment meant that the defendant also abandoned the data stored on the phone. In support of the defendant’s appeal, we urged the Ninth Circuit to reverse the district court’s ruling and hold that the Fourth Amendment’s abandonment exception does not apply to cell phones: as it must in other circumstances, law enforcement should generally have to obtain a warrant before it searches someone’s cell phone.

Cell phones differ significantly from other physical property. They are pocket-sized troves of highly sensitive information with immense storage capacity. Today’s phone carries and collects vast and varied data that encapsulates a user’s daily life and innermost thoughts.

Courts—including the US Supreme Court—have recognized that cell phones contain the “sum of an individual’s private life.” And, because of this recognition, law enforcement must generally obtain a warrant before it can search someone’s phone.

While people routinely carry cell phones, they also often lose them. That should not mean losing the data contained on the phones.

While the Fourth Amendment’s ”abandonment doctrine” permits law enforcement to conduct a warrantless seizure or search of an abandoned item, EFF’s brief explains that this precedent does not mechanically apply to cell phones. As the Supreme Court has recognized multiple times, the rote application of case law from prior eras with less invasive and revealing technologies threatens our Fourth Amendment protections.

Our brief goes on to explain that a cell phone owner rarely (if ever) intentionally relinquishes their expectation of privacy and possessory interests in data on their cell phones, as they must for the abandonment doctrine to apply. The realities of the modern cell phone seldom infer a purpose to discard the wealth of data they contain. Cell phone data is not usually confined to the phone itself, and is instead stored in the “cloud” and accessible across multiple devices (such as laptops, tablets, and smartwatches).

We hope the Ninth Circuit recognizes that expanding the abandonment doctrine in the manner envisioned by the district court in Hunt would make today’s cell phone an accessory to the erosion of Fourth Amendment rights.

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