After 180 days in the U.S., email messages lose their status as a protected communication under the Electronic Communications Privacy Act, and become just another database record. This means that a subpoena instead of a warrant is all that's needed to force Google to produce a copy. Other countries may even lack this basic protection, and Google's databases are distributed all over the world. Since the Patriot Act was passed, it's unclear whether this ECPA protection is worth much anymore in the U.S., or whether it even applies to email that originates from non-citizens in other countries.

Google's relationships with government officials in all of the dozens of countries where they operate are a mystery, because Google never makes any statements about this. But here's a clue: Google uses the term "governmental request" three times on their terms-of-use page and once on their privacy page. Google's language means that all Gmail account holders have consented to allow Google to show any and all email in their Gmail accounts to any official from any government whatsoever, even when the request is informal or extralegal, at Google's sole discretion.