California Public Employees’ Retirement System (Calpers), the biggest U.S. public pension fund, is trying to ban a law firm from representing a creditor in the bankruptcy of San Bernardino, Calif., Bloomberg News reported on Friday. Calpers accused the law firm of Winston & Strawn LLP of being “deceptive” by hiring several key lawyers who had been working for the pension fund in the bankruptcies of the cities of San Bernardino and Stockton, Calif. Winston & Strawn represents creditor National Public Finance Guarantee Corp., which opposes Calpers in the two bankruptcies, the pension fund said in court papers filed on Friday. The Winston & Strawn attorneys had been employed in the Charlotte, North Carolina, office of K&L Gates, the law firm representing Calpers in the bankruptcies. National and other creditors have complained that Stockton city officials were trying to force them, but not Calpers, to take less than they are owed. The same disputes CalPers is engaged in over Stockton also will have to be resolved in the San Bernardino case, the pension fund said.