Sens. Jon Tester and Max Baucus joined 24 other senators in sending a letter to Director of National Intelligence James Clapper asking him to justify the collection of Americans’ phone and personal information under the Patriot Act.

“We are concerned that by depending on secret interpretations of the Patriot Act, this program essentially relied for years on a secret body of law,” Tester and Baucus said in a joint press release. “This prevented our constituents from evaluating the decisions that their government was making and will unfortunately undermine trust in government more broadly.”

In their June 27 letter, the senators asked Clapper to reveal how long the National Security Agency used the Patriot Act to obtain large amounts of Americans’ records and whether the agency used the law to collect other types of information.

Tester, who has voted to repeal the Patriot Act several times, said surveillance programs authorized under the law could be used for bulk collection of records beyond basic phone data. He also said the government may be able to expand its collection of business records to private financial, medical and consumer records.

In the wake of recent revelations that the Foreign Intelligence Surveillance Court secretly granted the National Security Agency access to Americans’ phone and Internet records without their knowledge, Tester called on the Privacy and Civil Liberties Oversight Board, which investigates national security measures, to make sure they do not violate the privacy and civil liberties of law-abiding Americans and to begin investigating the government programs. The board members recently met with President Obama and are reviewing the government’s surveillance programs.

While acknowledging that the way in which the revelations were made public was “regrettable,” the senators said they believed the “bulk collection and aggregation of Americans’ phone records has a significant impact on Americans’ privacy that exceeds the issued considered by the Supreme Court in Smith v. Maryland.”

The senators also acknowledged that privacy rights should be weighed against the threat to national security, but they wanted to know from Clapper “more details about why you believe that the bulk phone records collection program provides any unique value.” The senators wanted to know more than just about “a few cases.”

The senators also expressed concern that “by depending on secret interpretations of the Patriot Act that differed from an intuitive reading of the statute, this program essentially relied for years on a secret body of law.”

The 25 senators provided Clapper with a list of seven questions, from how long the NSA has engaged in bulk phone record collection to descriptions of employment status of all persons who conceivably could have had access to this data.