The state attorney general’s office on Thursday won a legal battle over access to 20 boxes of records seized in an Aug. 23 search of the House Democratic research offices.

House Democrats had challenged a ruling by the judge supervising an investigative grand jury that is looking into millions of dollars in bonuses paid to legislative employees. The state Supreme Court on Thursday denied the caucus’ petition.

Court filings by the Democrats, as well as the attorney general’s office, are all sealed. The Supreme Court’s four-sentence order said the decision was unanimous, but Justice Thomas Saylor did not participate.

At issue was a Sept. 26 order by Judge Barry F. Feudale Jr. in which he said the investigators could review records in the seized boxes. He concluded that the boxes contained files — mostly from the 1990s — that appeared campaign-related, including opposition research, voter registration data and “incumbency protection” plans.

What is known about the dispute comes from a slightly redacted version of Feudale’s order filed in Dauphin County court two weeks ago. In it, the judge disclosed that the grand jury was investigating possible violations of the state ethics and election laws, theft, misapplication of public property and dealing in the proceeds of unlawful activities.

Lawyers for the House Democrats argued that the records seizure and Feudale’s private review of the records violated constitutional separation-of-powers principles, the judge wrote.

“I do not see this case as one that implicates a constitutional crisis or is it, given the unique facts set forth herein, one that is likely to be replicated,” he wrote.

A “limited number” of the records were arguably protected by legislative privilege, he said.

He denied government investigators access to an 11-page document involving a Democratic representative’s “intimate affairs” and said it “begs the question of why the caucus had such a document and what use or misuse was intended.”

In his order, Feudale said the boxes would remain secured until further order of the supervising judge or the state Supreme Court. Feudale was filling in for the grand jury’s supervising judge, Judge Harold Thomson, who was traveling in Europe at the time.

Attorney General Tom Corbett’s office and the grand jury are looking into whether any of the bonuses granted by all four caucuses in 2005-06 were illegal rewards for campaign work. State workers cannot campaign on state time, and state government resources may not be used for electioneering.

Tom Andrews, a spokesman for House Majority Leader Bill DeWeese, D-Greene, said the caucus is cooperating with the investigation but would not comment on grand jury matters.

Kevin Harley, a spokesman for Corbett, declined comment. The grand jury operates in secrecy, although subpoenas have been issued to both the Democrats and Republicans in the House.