King & Spalding's prior legal work for WhatsApp Inc. should not disqualify the firm from representing an adversary that was sued by the popular text messaging service in California federal court, lawyers for the firm told a judge Friday.

WhatsApp, represented by Cooley LLP, sued King & Spalding client NSO Group Technologies last year over claims the Israeli cybertechnology company exploited the messaging platform in an effort to gain unauthorized access to user communication. NSO has denied the allegations.

WhatsApp's lawyers contend King & Spalding's work for the company in a sealed matter four years ago has given the firm an unfair advantage in the pending case in Oakland's federal trial court. The Cooley lawyers argued in their disqualification papers that the lawsuit against NSO is substantially related to the earlier sealed matter and that King & Spalding acquired confidential information material to the pending litigation.