The four magic circle firms handed subpoenas this year by Enron’s New York bankruptcy examiner are refusing to hand over client documents amid fears of exposure to breach of confidentiality claims.

It is understood that Freshfields Bruckhaus Deringer, Slaughter and May, Clifford Chance and Linklaters have all indicated they will not hand over information covered by client confidentiality to the bankruptcy court’s investigation into the failed energy giant without their clients’ permission.