Federal District Court Judge James F. Holderman ruled recently that Chicago-based accounting firm BDO Seidman does not have to turn over confidential documents while it defends government charges that it sold abusive tax shelters, according to The New York Times.

According to Judge Holderman’s decision, most of the 110 client documents sought by the Internal Revenue Service are protected by attorney-client privilege, the Times reported. The judge did uphold a government motion requiring the accounting firm to turn over six documents; according to the paper, BDO Seidman has already provided the IRS with the documents, edited by the firm.

The documents concern communications between BDO Seidman and three law firms regarding tax shelters, wealthy clients who bought them through BDO Seidman, or both, according to the report. The law firms are Brown & Wood (now Sidley Austin Brown & Wood) in Chicago; DeCastro, West, Chodorow, Glickfeld & Nass in Los Angeles; and Proskauer Rose in New York.

According to the report, Brown & Wood and DeCastro West wrote legal opinion letters certifying that the shelters bought by BDO clients through the firm were legitimate, while Proskauer Rose advised BDO Seidman on the shelters.

“Evidence of any such coordinated partnership between BDO Seidman and the three outside law firms is lacking,” the judge wrote, according to the Times. He reportedly added that the evidence of favorable opinion letters “standing alone” — even though he had not reviewed them — “are not enough for this court to conclude that the outside law firms and BDO were promoters.”

The ruling was somewhat of a surprise given. In May, in a case involving the government’s probe of KPMG, a federal judge in Washington wrote that Brown & Wood’s favorable opinion letters were “an orchestrated extension of KPMG’s marketing machine” for abusive tax shelters, according to the Times.