Let's talk about "Coercive Sex".

[Major Nikon]

81. Even their definition leaves a lot to be desired

First they say...

consent cannot be given by someone who is not of sound mind and body

Then they say...

Someone who is drunk, high, unconscious or mentally incompetent may not be able to give consent to a sexual act.

Which seemingly contradicts itself. First they suggest consent can't be given if someone is intoxicated, they they say they "may not be able" to give consent.

Here's a more informative site which actually lists the relevant statues and case law:

In a rape case in which lack of consent due to intoxication is an issue, the prosecution must prove not only intoxication, but 1) that the intoxication rendered the complainant incapable of consent and 2) that the defendant knew or should have known that the condition rendered the complainant incapable of consenting.

http://www.lawlib.state.ma.us/subject/about/rape.html

So this seems to cover the issue if both parties are drunk or high. Otherwise it would be problematic to determine who raped whom.