Walsh must disclose if City Hall officials received federal subpoenas under public records law

Mayor Martin J. Walsh’s administration will be required to acknowledge whether federal subpoenas were served on City Hall, according to a ruling by the state supervisor of records made public Monday.

In a ruling dated Friday, supervisor Shawn A. Williams said the City of Boston failed to meet the legal burden for withholding records from the public when city officials denied a Globe request for documents related to any US attorney investigation in City Hall.

The city must say within 10 days whether it has received federal subpoenas for documents, or provided any records to federal investigators since January 2014, when Walsh took office, Williams wrote.

If the city has exchanged documents with federal investigators, it must produce copies or cite specific exemptions from the state public records law to justify withholding them, Williams wrote to Laura Oggeri, the city’s chief communications officer.

The Globe reported Sunday that Walsh had been drawn into a widespread federal investigation into tactics of local unions, which had brought scrutiny to Walsh’s time as a labor leader before he was elected mayor. In reporting that story, the Globe on April 1 filed a request under the state public records law for all documents received from the US Attorney’s office, including subpoenas, and all records provided to federal investigators since Walsh took office.

The city denied the request April 11, saying, “If the city were to receive a subpoena from law enforcement and provide information … we would be requested by law enforcement to keep it confidential to preserve the integrity of their investigation.” In a second response April 20, the city cited an exemption to the public records law meant to protect material compiled by law enforcement.

Williams wrote that based on the city’s responses, “it is unclear what type of records would be withheld and how disclosure could alert suspects to the activities of investigative officials, reveal confidential investigative techniques, or disclose the identities of voluntary witnesses, informants or complainants.

“Therefore, it is unclear how disclosure of the responsive records would probably so prejudice the possibility of effective law enforcement that such disclosure would not be in the public interest,” as required by the law enforcement exemption in the law, he wrote.

A Walsh administration spokesperson did not immediately respond to a request for comment.