The Internal Revenue Service (IRS) has claimed that agents do not need warrants to read people's emails, text messages and other private electronic communications, according to internal agency documents.
The American Civil Liberties Union (ACLU), which obtained the documents through a Freedom of Information Act request, released the information on Wednesday.
Under the Electronic Communications Privacy Act (ECPA) of 1986, government officials only need a subpoena, issued without a judge's approval, to read emails that have been opened or that are more than 180 days old.
Privacy groups such as the ACLU argue that the Fourth Amendment provides greater privacy protections than the ECPA, and that officials should need a warrant to access all emails and other private messages.
Traditionally, the courts have ruled that people have limited privacy rights over information they share with third parties. Some law enforcement groups have argued that this means they only need a subpoena to compel email providers, Internet service companies and others to turn over their customers' sensitive content.
But in 2010, a federal appeals court ruled that police violated a man's constitutional rights when they read his emails without a warrant.
Despite the court decision, U.S. v. Warshak, the IRS kept its email search policy unchanged in a March 2011 update to its employee manual, according to the ACLU.
In an October 2011 memo obtained by the ACLU, an IRS attorney explained that the Warshak decision only applies in the Sixth Circuit, which covers Kentucky, Michigan, Ohio and Tennessee.
But the attorney noted that if a service provider fought the search request, it would likely result in "protracted litigation," meaning that any leads from the emails would be "stale" if the IRS ever obtained them.
The IRS did not respond to a request to comment.
The ACLU also submitted requests for documents from the FBI and the Justice Department on their policies for emails searches, but has not received responses yet.
Lawmakers in both chambers are working on legislation that would update the ECPA to require a warrant for emails and other private online messages.
At a hearing last month, Elana Tyrangiel, the acting assistant attorney general for the Justice Department's Office of Legal Policy, agreed that there is "no principled basis" for treating emails differently depending on how old they are.