On September 3, 2010, a federal judge in the Southern District of New York granted the government's motion to disqualify attorneys from Sonnenschein, Nath & Rosenthal LLP from representing both an alleged tax fraud conspirator and a cooperating government witness in the same case. Sonnenschein had recently assumed the representation of Defendant Denis Field, the former Chairman of accounting firm BDO Seidman LLP who is charged with participating in a tax fraud conspiracy from 1994 to 2005, for the limited purpose of determining whether the government interfered with Field's right to counsel during its investigation by pressuring BDO to stop paying his legal fees in 2004. Sonnenschein also represented Adrian Dicker, a former BDO partner and close associate of Field who was indicted and pled guilty in a separate proceeding. The government plans to call Dicker at trial to testify against Field.

In his opinion, Judge William Pauley said that Sonnenschein's representation of both individuals presented a "clear conflict of interest," in spite of the fact that the attorneys worked in separate offices and erected an ethical wall to protect client confidences. Judge Pauley reasoned that given the factual overlap between Sonnenschein's representations, Dicker could possess discoverable information that Field would wish to obtain, thereby placing the attorneys in an adversarial situation that would be "wholly untenable." Furthermore, Judge Pauley found that while Dicker's interests were protected by the attorney-client privilege, his refusal to waive any conflict suggested a level of discomfort with Sonnenschein's dual representation. Balancing the competing interests of the parties, the court found that its duty to protect Dicker's interests as a cooperating witness and his right to conflict-free counsel mandated that it disqualify Sonnenschein from its limited, and more recent, representation of Field. Order.