From crimelibrary.com, your major categories of rapists are these:
Power-reassurance: That’s what law enforcement calls the “gentleman rapist.” He has a complex fantasy of a consensual relationship with a woman.
Power-assertive: That’s the individual who believes that he is entitled to do whatever he wants to women. They’re to be used for his gratification. His fantasies are minimal.
Anger-retaliatory: This person assaults because he’s motivated by anger and he’s getting even with women for real or imagined wrongs. He has almost no fantasy. He simply strikes.
Anger-excitation: He’s a sexual sadist. He’s punishing women because he believes them to be evil and powerful, so he’s trying to take away that power. He has deep and complex fantasies.
Opportunistic: He’s there to commit another crime like robbery or burglary. The victim is there and he simply seizes the opportunity. He’s frequently under the influence of alcohol or drugs. If he starts robbing and raping repeatedly, he gets classified into one of the major categories.
Gang rape: This involves three or more offenders and you always have a leader and a reluctant participant. Those are extremely violent, and what you find is that they’re playing for each other’s approval. It gets into a pack mentality and can be horrendous.
Opinion: Having read a little bit about a few serial rapists/killers, it’s obvious to me that they have severe psychological problems. This does not in any way exonerate them from responsibility in any crime they commit, but it is clear nonetheless that many of them are more or less mentally ill. A person who feels compelled to wash his hand ten times an hour and lock all the doors six times before bed is termed a person with compulsions, and if these compulsions are severe enough, he may be diagnosed with Obsessive-Compulsive Disorder. Shouldn’t there also be a disorder for people who feel compelled to force sex on others?
My questions: Should someone be doing psychological testing on these criminals? Should there be diagnostic categories for them in psychology and psychiatry (currently there are not)?
If there were such categories, would that minimize the criminality of such behavior and allow rapists to say “oh, but I have paraphilic rape disorder, I can’t help it,” and would they then get off on an insanity defense or be treated less harshly in terms of incarceration time? Where should the line be drawn between a common ordinary rapist (say it happened on a date and he just kept going after she said no) and a mentally ill rapist?