A woman can induce a man to have a hard on but she does not necessarily have to to have sex with him against his will. If she puts his dick into her mouth or do any sexual activity against his will she is violating him. The charge is sexual assault which is as serious as penetrative rape.
If a man has a hard on then its going to be hard (pun intended) to convince anyone that he was not into it. Ladies and gentlemen of the jury, his dick was hard, my client naturally assumed that he was excited about the prospect and his objections just a form of S&M play. Lets face reality - a hard-on is nature's most honest compliment. He might feel embarrassed, he might fear getting caught or maybe his girlfriend walking in needed a quick desperate excuse.
'I was raped !' '
Why were you hard ?' ' Oh, it was the Viagra. She made me eat it and my dick got hard so even though I was repulsed by her
sexy .. I mean .. ugly body - I could not control it.'
In conclusion Ladies and gentlemen of the jury - if you let this pass then from this day forward every cheating married man will say that he was raped. The defense rests..