Appellate attorneys for Bill Cosby have argued that district attorneys have the power to end a criminal investigation by promising that the subject of investigation will never be prosecuted for the alleged crime.

In a brief filed with the Pennsylvania Superior Court on Monday, Cosby’s attorneys said former Montgomery County District Attorney Bruce L. Castor Jr. had the authority to promise that Cosby would never be prosecuted for sexual assault allegations brought by Andrea Constand in 2005. In addition, they argued that the District Attorney’s Office had no valid reason for its 10-year delay in bringing charges against Cosby.