The Criminal Code says:
- (1) A person commits an assault when (a) without the consent of another person, he applies force intentionally to that other person,
directly or indirectly
Touching is applying force, even if it is slight. The law also says (same section) that apparent consent evidenced by submission isn't actually consent:
(3) For the purposes of this section, no consent is obtained where the
complainant submits or does not resist by reason of
(a) the application of force to the complainant or to a person other
than the complainant;
(b) threats or fear of the application of force to the complainant or
to a person other than the complainant;
(c) fraud; or
(d) the exercise of authority.
This pretty much means that consent is always required. If you are wrong about there having been consent and you end up being charged, you can explain why you thought there was consent, and the judge may find the story sufficiently plausible that you can use that as a defence, because:
4) Where an accused alleges that he believed that the complainant
consented to the conduct that is the subject-matter of the charge, a
judge, if satisfied that there is sufficient evidence and that, if
believed by the jury, the evidence would constitute a defence, shall
instruct the jury, when reviewing all the evidence relating to the
determination of the honesty of the accused's belief, to consider the
presence or absence of reasonable grounds for that belief.
Here is a model jury instruction pertaining to consent
Third – Did (NOC) consent to the force that (NOA) applied? To decide
whether (NOC) consented to the physical contact, you must consider
(NOC)’s state of mind. Consider all the evidence, including the
circumstances surrounding (NOA)’s physical contact with (NOC), to
decide whether (NOC) consented to it. Take into account any words or
gestures, whether by (NOA) or (NOC), and any other indication of
(NOC)’s state of mind at the time. Just because (NOC) submitted or did
not resist does not mean that (NOC) consented to what (NOA) did.
Consent requires (NOC)’s voluntary agreement, without the influence of
force, threats, fear, fraud or abuse of authority, to let the physical
contact occur.
The instruction pertaining to the "honest but mistaken belief in consent" defence goes like this:
(NOA)’s position is that s/he was unaware that (NOC) did not consent.
In fact, it is his/her position that s/he honestly believed that (NOC)
consented to the physical contact in question. A belief is a state of
mind, in this case, (NOA)’s state of mind. To determine whether (NOA)
honestly believed that (NOC) consented to the physical contact in
question, you should consider all the circumstances surrounding that
activity. Take into account any words or gestures, whether by (NOA) or
(NOC), and any other indication of (NOA)’s state of mind at the time.
(NOA)’s belief that (NOC) consented to the physical contact must be an
honest belief, but it does not have to be reasonable. However, you
must consider whether there were reasonable grounds for (NOA)’s
belief; the presence or absence of reasonable grounds may help you
decide whether (NOA)’s belief was honest. Look at all the
circumstances in deciding this issue. Do not focus on only one and
ignore the rest. You must consider all the evidence, including
anything said or done in the circumstances. Use common sense. (NOA)
does not have to prove that s/he honestly believed that (NOC)
consented to the physical contact. Rather, the Crown must prove beyond
a reasonable doubt that (NOA) had no such belief.
In other words, if the story is believable, the jury might believe it. Asking for each and every kind of contact can be annoying and a little silly, but if you might be at risk, better silly than sorry.