In my 47 years of sexual activity, I can't think of a single instance when there was not explicit verbal agreement and a clear demonstration of desire to engage in sexual activity. It's just not that difficult.
But can you prove that verbal agreement took place? Your mere assertion won't mean much. Would you now recommend recording all intimate conversations that may lead to sex?
The real question is, why would I need to, if the need has never arose in 47 years? If any recommendation is due, it would be to know the person with whom you are about to have sex, well enough to know if this kind of thing is likely to be an issue. A secondary recommendation would be to not have sex with impaired people. As I said above, it's not that difficult to avoid putting oneself in jeopardy.
This law does not seem to be specific to impaired people. Unless I missed something? And just because you haven't had a problem doesn't mean you never will or nobody ever does.