Is an adulterer or adulteress sinful if forced into adultery, and what is the ruling on that?

As for a woman who is forced into adultery, there is no accountability upon her. However, regarding a man who is forced into it, scholars have differed. Some are of the view that it is inconceivable for him to be coerced, because penetration cannot occur without an erection, which is evidence of intention and will. Others are of the view that there is no accountability upon him, because an erection is a natural, involuntary physiological response that he cannot prevent.