Late last month, United States Magistrate Judge Waxse denied a government application for a broad email warrant under the Stored Communications Act (18 U.S.C. 2701, et seq.) and Rule 41 of the Federal Rules of Criminal Procedure, after finding that the application violated the Fourth Amendment's probable cause and particularity requirements.
It's a doozy of an opinion---a must read for anyone challenging a warrant for digitally stored information.
In the opinion, Judge Waxse traces the history of recent rulings across the country on similar warrant applications. He concludes that courts allowing warrants for all Electronically Stored Information (ESI) associated with a target email account have failed to give proper weight to the privacy rights of account holders. He explains that "[t]he chief aim of this Court's email (and cellular phone) opinions has been preventing the issuance of general warrants in the context of ESI." And he explores the concept of digital privacy in great detail, emphasizing that when it comes to ESI "[t]he privacy implications are enormous."
In the end, Judge Waxse insists on search protocols and limitations on the government's search of the requested information. He suggests a number of these (categorical limitations, keyword limitations, special masters, filter teams, use restrictions, etc.), and grants the government leave to resubmit its application along with a suitable search protocol.