The court’s ruling was essentially a simple one. The government is currently allowed to deploy “pen registers”—devices that can record every telephone number a suspect dials—without a warrant, since a list of telephone numbers is considered only addressing information and not content. This is analogous to the US Postal Service, where anyone can read information on the outside of an envelope but can’t look at the contents. The Ninth Circuit ruled that grabbing e-mail addresses and IP addresses without a warrant amounts to the same thing, and is legal. This is the first time that a federal court has ruled on the issue.
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