Walgreen Co. has ramped up a court fight in Washington against Crowell & Moring, accusing the major U.S. law firm of breaching ethics guardrails by taking positions that are adverse to the national pharmacy chain despite having earlier worked for the company on matters it contends are related.

Lawyers for Walgreens on Tuesday filed an amended complaint that asked a District of Columbia Superior Court judge to disqualify Crowell from an arbitration proceeding in which the firm is representing the insurance carrier Humana Inc. against Walgreens. The attorneys also urged the judge, Hiram Puig-Lugo, to strip legal fees “that Crowell has received or in the future will receive in connection with actions in which it is acting adversely to Walgreens.”