In Iowa v. Collier, there were wildly differing accounts given of a BDSM incident, but the judge refused to let the jury consider the question of consent. The Appellate Court upheld the conviction and ruled that consent was not a defense. Significantly, the Iowa law on assault was in most ways similar to the Model Penal Code.
Provided, that where the person doing any of the above enumerated acts, and such other person, are voluntary participants in a sport, social or other activity, not in itself criminal, and such act is a reasonably foreseeable incident of such sport or activity, and does not create an unreasonable risk of serious injury or breach of the peace, the act shall not be an assault.
I.C.A. § 708.1
The court’s moralistic tone in rejecting the consent defense is a good illustration of the type of thinking that seems to underly most judges’ handling of BDSM assault cases:
The foregoing discussion compels us to conclude that, in the present case, the legislature did not intend sadomasochistic activity to be a "sport, social or other activity" under section 708.1. We are hesitant to give a precise definition of this term and believe it is more appropriate that its meaning be interpreted on a case by case basis. However, it is obvious to this court that the legislature did not intend the term to include an activity which has been repeatedly disapproved by other jurisdictions and considered to be in conflict with the general moral principles of our society. In fact, the statutory provision in question specifically excludes activities which would "create an unreasonable risk of serious injury." There can be little doubt that the sadomasochistic activities involved in this case expose persons to the very type of injury deemed unacceptable by the legislature. Were we to follow defendant's broad interpretation of "social activity," street fighting, barroom brawls and child molestation could be deemed acceptable social behavior, since such conduct is considered acceptable by some segment of society.
State v. Collier 372 N.W.2d 303, 307 (Iowa App.,1985)