SEATTLE — Washington’s Supreme Court has agreed to review a decades-old law that investigators have used to secretly obtain private bank, phone, email and other records without showing probable cause — the standard that would normally be required to get a warrant for the information.

At issue are little-known “special inquiry judge” proceedings –confidential hearings in which a specially designated judge can review evidence or listen to witness testimony as prosecutors work toward filing charges in a criminal investigation. The procedure, created by the Legislature in 1971, allows the judge to issue subpoenas for evidence, such as bank or phone records, at the request of a prosecutor who has “reason to suspect” crime.

That’s a lesser standard than probable cause, and defense attorneys say that’s part of the problem. Other concerns are that the law doesn’t require any representations to the judge to be made under oath, and — unlike with a traditional search warrant — information about the search doesn’t necessarily become public.

“Where you are going into an area of privacy protected under Washington law, that subpoena must meet the standard of a warrant: probable cause, supported by oath or affidavit,” said David Donnan, a lawyer challenging the use of special inquiry judge proceedings in a King County case. “When you’re delving into financial documents, it does expose so much traditionally private information. It’s the sort of intrusion we try to protect against here in Washington.”

Under Washington’s Constitution, people can’t be disturbed in their private affairs without “authority of law.” Typically that is satisfied when investigators obtain a warrant.