The government seeks to sidestep these rules, asserting that emails you store in the cloud cease to belong exclusively to you. In court filings, it argues that your emails become the business records of a cloud provider. Because business records have a lower level of legal protection, the government claims that it can use its broader authority to reach emails stored anywhere in the world.

Courts have long recognized the distinction between a company’s business records and an individual’s personal communications. For example, the government can serve a subpoena on UPS to disclose business records that show where a customer shipped packages, but it must establish probable cause and get a warrant from a judge to look at what a customer put inside.

Similarly, the government can use a subpoena to obtain bank records that show when a customer accessed a safe-deposit box, but it needs a warrant to search the private papers kept inside. It may subpoena the business records containing a hotel’s guest registry, but it cannot take the diary in a guest’s hotel-room drawer except through a legal search and seizure.