Senate Judiciary Chairman Patrick Leahy (D-VT) announced late yesterday that he will bring legislation before the committee requiring law enforcement to use a probable-cause warrant to access all non-public internet communications such as email. This legislation is a key piece of efforts to reform the Electronic Communications Privacy Act (ECPA), first passed in 1986 and not substantially updated since.
In 1986 email was a novelty. Congress was so unsure of how to handle it that they treated it like a combination of phone call and letter. Lawmakers assumed that email would be largely transient and that companies providing email services wouldn't hold onto messages for long periods. As a result they structured ECPA so that email older than 180 days would be treated as discarded and receive a very low level of privacy protection.