A woman has a few drinks and chooses to sleep with a man she would not sleep with sober, the man has not committed a crime.
That's a legal gray area and there's been countless cases around those situations and they've gone both ways. In some ways it is a crime because a person cannot legally consent to something if they are impaired. Plenty of people have been prosecuted for sleeping with women who were intoxicated even if the intoxication came from their own actions.
e had no reason to believe Finn wasn't acting in her right mind either. Like others said, maybe he thought in public (med bay, hallways) she couldn't show her love for him but in private, after his last effort to woo her, she came around and came to him after hours, in his quarters.
That's too much of a "No means Yes" kind of way of looking at it. (Though, I suppose in this case the opposite.) She did a complete 180 on him, her entire personality and front to him changed, he should have been suspicious that something was up because she goes from threatening to talk to HR to wanting to be all over him (or all in him) in a flash, without ever saying "Hey, I have to keep a front in sickbay, but let's give it a go." She goes from constantly rebuffing his advances in sickbay, to yelling at him and threatening to report him to HR and throwing him out to fully wanting him? Alarm bells should have gone off in his [head] that she was under some kind of influence. People take Ecstasy and become overly amorous, if a woman from work knocked on my door, high on Ecstasy, and pleaded her endless desire to have sex with me I'd be suspicious. More so if she was someone I had a confrontational encounter with very recently to the extent she threatened me with some kind of action involving either work or legal authority.
I sometimes don't completely understand what people mean when they speak of "Rape Culture" in America and it's things like this that makes me sort of realize what it is they're talking about. People too willing to just excuse sexual encounters because there's some variable or unknown or we assuming some form of ignorance on the part of the person making the decisions of their own free will and that we should just shrug and accept it happened. Well, what about the victim? (In this case Dr. Finn.) It's not likely something we're going to see dealt with in the show but isn't she going to be slightly bothered or traumatized about her own memories of everything that happened to her the last few days? Alara got a shock entering her office but Finn is going to have to live with actually DOING these things and also be expected to continue working with the being who did this to her and even treating him in true medical situations.
Yaphit had more signs and clues thrown at him that Finn was
not interested in any manner, she had made that abundantly clear. He had NO reason to think her sudden 180 was a genuine turn and all previous encounters were the false ones put on due to situational circumstances. (Being sickbay.) He has countless cases of her saying "No, I'm not interested" and "No, Stop asking!" and he has ONE case of her coming in and "asking for it" out of the clear-blue (black?) sky.
And ignorance of something isn't an excuse. Yeah, Yaphit didn't know about the pheromone problem spreading around and he really didn't seem to think Finn was acting odd or seemed to be consciously taking advantage of her diminished capacity but he still should have known better. He has virtually no reason to think this was truly "her."
(I like to say that an episode of a show, particularly shows like this that take on topics, is as good as the discussion it creates. That's why I think "Majority Rule" was such a great episode because of all of the discussion it generated about our society and rush-to-judgment on little no information way of doing things socially. This episode is an exception, it's not good because of the discussion it's generating because it's not a discussion it intended to generate because it's not an issue it dealt with. It treats the stuff between Yaphit and Finn as "humorous." It's generating this discussion because it handled the topic poorly.
There would've been a lot more respect, from me, in this episode had Yaphit turned Finn down because it was clear to him she wasn't right in the head. Yeah it was his "dream" to have a night with her, but he wanted it to come from her and not from chemical influence.)