A woman dresses in a costume resembling the Statue of Liberty while holding a sign directing people to an office offering tax services on April 5, 2013 in Alhambra, California. - 

Before you sign that tax form today, are you sure there's nothing in your email inbox that might contradict what you’ve entered? New documents suggest the Internal Revenue Service (IRS) believes it doesn't need a warrant to look through email when investigating possible tax cheats.

"What we are talking about is only what the IRS thinks it has authority to do in its criminal investigations," says Nathan Freed Wessler, staff attorney at the ACLU's Speech, Privacy, and Technology Project. "It appears from all the documents that we reviewed and from their statements, that they still claim the authority to read at least some emails without getting a warrant from a judge."

The Electronic Communications Privacy Act, which governs this area, was passed in 1986 before the World Wide Web took hold. Critics point to many anomalies in the law, including the way it treats email stored on remote computers -- the Cloud -- as less private than email stored on a home computer. But in 2010, a federal court found that the government needs a court order to look at email in certain cases.

"So what the IRS believes today is a little less clear," says Purdue computer science professor Christopher Clifton. Clifton says much of the issue revolves around our expectations of privacy. If we expect something is private, it stands a greater chance of being protected from unreasonable searches by the Fourth Amendment of the Constitution.

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