In most BDSM assault cases, the testimony of a complaining witness (the injured person) is central to the case, and often there is conflict on the issue of consent between the defendant and the complaining witness. However, even where both participants agree that the acts in question were consensual, the courts have held that consent cannot be a defense. Thus, in Commonwealth v. Appleby, a 1980 Massachusetts case, the court said:
“Grimm’s consent to assault and battery upon him by Appleby by means of a dangerous weapon cannot absolve Appleby of the crime…”Commonwealth v. Appleby, 380 Mass.296, 311, 402N.E.2d 1051,1061 (Mass. 1980).