US Magistrate Judge Gabriel Gorenstein said Friday he had authorized a warrant to be served on Google Inc for the emails of an unnamed individual who is the target of a money laundering investigation.
Gorenstein said his decision ran counter to several other judges' rulings in similar cases that sweeping warrants give the government improper access to too many emails, not just relevant ones.
But he said the law lets investigators review broad swaths of documents to decide which are covered by warrants.
Google did not respond to a request for comment.
The ruling came three months after US Magistrate Judge James Francis in New York said prosecutors can force Microsoft Corp to hand over a customer's email stored in an Ireland data center.
Microsoft has appealed, in what is seen as the first challenge by a company to a warrant seeking data stored overseas.
Companies including Verizon Communications Inc, AT&T Inc, Cisco Systems Inc and Apple Inc have filed briefs in support of Microsoft, as has the Electronic Frontier Foundation, an advocacy group. A hearing is set for July 31 before U.S. District Judge Loretta Preska in New York.
The government's ability to seize personal information has grown more contentious since former National Security Agency contractor Edward Snowden leaked secret documents in June 2013 to media outlets outlining the agency's massive data collection programs.
In June, a unanimous U.S. Supreme Court ruled police generally need a warrant to search an arrested suspect's cellphone, citing privacy concerns.
Gorenstein's ruling joined a public debate playing out among several magistrate judges, who typically handle warrant requests. It is unusual to issue lengthy opinions on such matters particularly when, as in Gorenstein's case, the judge approves the application.
In April, John Facciola, a magistrate in Washington, D.C., rejected a warrant for the Apple email account of a defense contractor as part of a kickback investigation, one of several similar opinions he has authored recently.
Last year, a Kansas magistrate denied warrant applications for emails and records at Google, Verizon, Yahoo! Inc, Microsoft unit Skype and GoDaddy in a stolen computer equipment case.
Both judges said the warrants were overly broad.
On the other hand, several U.S. appeals courts have rejected motions to suppress such searches, Gorenstein said.
Hanni Fakhoury, a lawyer with the Electronic Frontier Foundation, applauded Gorenstein for explaining his reasoning in writing, though he said he disagreed with the analysis.
"The more voices and opinions we can add to the discussion, the better," he said in an email.