Senator Mike Lee, Republican of Utah, co-sponsored the Senate bill. He said in a recent interview that “like most Americans,” he was shocked to find that the 1986 statute was on the books.

“Almost every American thinks that it is frightening that we have a law that suggests that the government has the right to read your email after only 180 days,” Mr. Lee said. “It’s an easy issue in which to achieve bipartisan compromise and consensus.”

The bill would require a search warrant for access to electronic communications, with exceptions for some emergency situations. It would also require the government to notify individuals within 10 days that their information was being investigated. However, it does not address rules for location data, like GPS information from an individual’s cellphone.

The Senate Judiciary Committee approved the bill a year ago, but it has since stalled. One reason is resistance from federal investigating agencies that use subpoenas to gain access to electronic communications in civil cases, particularly the Securities and Exchange Commission.

“The S.E.C. cannot get a search warrant, so a bill that requires a warrant to obtain emails from an I.S.P. would undermine the S.E.C.’s ability to protect American investors and hold wrongdoers accountable,” said Andrew Ceresney, the director of the Division of Enforcement at the S.E.C., referring to Internet service providers. Instead, the S.E.C. would have to rely on an individual’s voluntary disclosure of digital content.

But some legal experts, and at least one appeals court, do not find that argument compelling. “The courts say that email on a server somewhere is like email in your virtual home,” said Orin S. Kerr, a professor at George Washington University Law School. “We wouldn’t say the S.E.C. should have the power to tell your landlord to break into your apartment and get evidence. The same rule should apply.”

The United States Court of Appeals for the Sixth Circuit, in Cincinnati, ruled in 2010 that part of the Electronic Communications Privacy Act was unconstitutional. Since the decision, most major technology companies have required a search warrant for customers’ content.