Officials at the FBI do not need a warrant to read citizens' private emails, according to documents uncovered by the American Civil Liberties Union (ACLU).
Documents that came to light following an ACLU Freedom of Information request say FBI agents can use a loophole in the Electronic Communications Privacy Act (ECPA) to read private emails without a warrant.
The loophole in the ECPA allows government agencies to snoop through private emails that are older than 180 days.
An FBI handbook uncovered by the ACLU said: "If the contents of an unopened message are kept beyond six months or stored on behalf of the customer after the email has been received or opened, it should be treated the same as a business record in the hands of a third party, such as an accountant or attorney.
"In that case, the government may subpoena the records from the third party without running afoul of either the Fourth or Fifth Amendment."
ACLU speech, privacy and technology project staff attorney Nathan Freed Wessler said in a blog post: "These records show that federal policy around access to the contents of our electronic communications is in a state of chaos.
"The FBI, the Executive Office for US Attorneys, and Department of Justice (DOJ) Criminal Division should clarify whether they believe warrants are required across the board when accessing people's email."
The loophole was also discovered to be used by the Internal Revenue Service (IRS) last month. ACLU staffers uncovered that the IRS was snooping through personal emails without a warrant following another Freedom of Information request. IRS officials have denied any wrongdoing. It said in a recent statement that the IRS does not use email to target taxpayers.
The Senate Judiciary Committee (SJC) recently called for the ECPA to be amended and has earmarked an updated version of the bill for a Senate vote.
Comcast's £29.7bn winning bid more than twice the £13.7bn Rupert Murdoch valued Sky at just eight years ago
A nuclear strike has been considered, but Bruce Willis is nowhere in sight
Spray-on antenna could enable seamless integration of antennas with everyday objects
Parker Solar Probe, TESS and GOLD missions will deliver exciting data, claims NASA