The Justice Department has dropped its long-standing objection to proposed changes that would require law enforcement to get a warrant before obtaining e-mail from service providers, regardless of how old an e-mail is or whether it has been read.

“There is no principled basis” to treat e-mail less than 180 days old differently than e-mail more than 180 days old, Elana Tyrangiel, acting assistant attorney general in the department’s Office of Legal Policy, said Tuesday.

Tyrangiel, testifying before a House Judiciary subcommittee, also said that opened e-mail should have no less protection than unopened e-mail.

Current law requires law enforcement to obtain a warrant before gaining access to e-mail that is 180 days old or less if it has not been opened. But prosecutors may obtain e-mail older than 180 days, or any e-mail that has been opened, with a mere subpoena.

Prosecutors can obtain a subpoena if they believe that the material sought would be relevant to an investigation. For a warrant, they need to convince a judge that the e-mail contains probable cause of a crime.

The department’s shift means that legislative efforts to amend the 1986 Electronic Communications Privacy Act stand a better chance at succeeding. Lawmakers have drafted legislation that would impose a warrant requirement for all e-mail held by commercial providers.

In practice, since a 2010 ruling by the U.S. Court of Appeals for the 6th Circuit requiring a warrant for stored e-mail, most large commercial e-mail providers, such as Google and Yahoo, have adopted that standard.

That has made it harder for the department to argue that a warrant requirement undermines public safety, said Jason Weinstein, a former deputy assistant attorney general in the criminal division.

“It’s a good thing that the department has taken this step and publicly acknowledged that some of these distinctions are no longer meaningful,” he said.

The department’s “reversal is a welcome step forward,” said American Civil Liberties Union legislative counsel Chris Calabrese. “They seem to be agreeing with companies and groups across the political spectrum that a warrant is the right standard for e-mail.”

The Justice Department does not support a uniform warrant standard for all e-mail. In her testimony, Tyrangiel argued that civil investigative agencies that do not have warrant authority, such as the Securities and Exchange Commission, must not lose their ability to obtain e-mail with a subpoena.