So having sex with someone is quite risky. Probably best to make the decision when you're not drunk.
Having unprotected sex can be quite risky (in terms of contracting an STI). It would indeed be best to make that decision when you're sober. Leaping off a bridge is quite risky, and people make that decision while drunk too. Frankly making
any decision while drunk is probably not a good idea. Are you suggesting people should be prohibited from making decisions while drunk?
Well you could always use the "reasonable person" standard to what constitutes informed consent.
That doesn't help. The question is what constitutes "informed". That has nothing to do with the reasonableness of the person and everything to do with the information available to them.
"Despite her inability to walk straight and her breath smelling of vomit, I believed she was perfectly capable of making an informed decision to have sex with me."
Like I said, unless you can first establish what "informed consent" means in relation to sex, discussing whether a given person was in a state to meet that threshold is irrelevant.
Medical exams usually require participation by the patient. E.g., "Now if you'll just curl up on your left side Mr. Smith..."
Do you accept that there's a difference between agreeing to do something, and agreeing to let someone do something to you? Yes or no?
It depends on what is being tested for.
Unless you're using instruments the procedure would not normally be considered invasive. (Even with an instrument it's minimally invasive).
There are two aspects to consent in a medical scenario. One is informed consent, the other is medical consent.
Informed consent is for the purpose of protection against professional negligence, and establishes duty of care owed to the patient. Obviously when two people agree to have sex (assuming it's not prostitution) professional negligence and duty of care are irrelevant. When a person gives informed consent they are confirming that they accept the doctor in question is competent to perform the procedure in question, and they accept that they know what the doctor is going to do.
The threshold for medical consent is rather low, and far more comparable to sexual consent as it protects the medical practitioner from a charge of assault or battery. A person can give medical consent while drunk. Indeed, if the person is so drunk they cannot give consent, medical consent is
assumed. Medical consent is essentially what you give any time you allow a medical practitioner to touch you. Unlike informed consent, which normally requires you to sign a form, medical consent can be given as simply as by responding to a doctor's request to "lift up your shirt" or similar.