As regular readers know, one of the big issues in computer search and seizure law that I often write about is how to limit computer warrant searches. If everything needs to be searched to find the evidence, and information outside the scope of the evidence sought can be used in plain view, doesn't a search of a computer with a warrant result in a general search — the kind that the Fourth Amendment was enacted to prevent. My own answer to this puzzle is that the Fourth Amendment requires use restrictions for digital searches. The whole computer can be searched, but evidence outside the scope of the warrant cannot be used.
In the last year or two, however, a few state courts have tried to limit computer searches through novel interpretations of the particularity requirement. I think this is wrong, and I thought I would explain why.
Consider a recent example from the Michigan Court of Appeals, People v. Carson. In Carson, the government obtained a search warrant to search a cell phone seized incident to arrest as required by Riley v. California. The government had arrested Carson for working with his girlfriend to steal $70,000 in cash from his neighbor's safe. The government then obtained a warrant to search the phone for "records or documents pertaining to the investigation of Larceny in a Building and Safe Breaking." The officers searched the phone and found text messages between Carson and his girlfriend in which they discuss the crime. The text messages were then used at trial to help prove the crime.
