The closest possible prohibition is found in s. 286.1 of the Criminal Code, which makes it an offence to pay for the "sexual services of a person."
"Sexual services" is not a defined term. The Department of Justice provides its opinion about what this term might cover, but that is not determinative.
In relation to a charge of the previous version of this prohibition (which also used the term "sexual services"), counsel was unable to direct the judge to a definition of the term, and the judge was unable to find one (2015 ABPC 241). The judge adopted a test that requires the service to include "some sexually suggestive physical act on the part of the person providing the sexual service". This is a test somewhat stricter than the one proposed by the Department of Justice in that in addition to merely being "sexually stimulating or gratifying," there physical act itself must be "sexually suggestive."
[50] What is a “sexual service”? Counsel have not directed me to, nor have I been able to find a definition of the term “sexual services”.
[51] Sexual services” would clearly include any type of sexual intercourse,
or physical contact for purposes of masturbation. It would also
include posing for nude photographs. A request “to touch or feel
the breasts of the [female] complainant” is an attempt to obtain the
sexual services of the complainant. In my view, “sexual services” would
also include dancing in a sexually provocative or stimulating fashion.
In terms of a general definition, I think the phrase “sexual favours
rendered ...for the sexual gratification of the customer” is sufficient.
[52] However, I am of the view that the “sexual services” or
“sexual favours for the sexual gratification” of a person requires
that there be some sexually suggestive physical act on the part of the
person providing the sexual service. The sexually suggestive physical
act may be many things, such as posing nude, or sexually suggestive
dancing, or suggestively removing clothing. That list is not
exhaustive, and, with the creativity of the human mind, I doubt one
could ever create an exhaustive list. However, the common element is
that some sort of sexually suggestive physical act is necessary to
constitute the sexual service.
[53] In the case at bar, the accused had M.C. engage in what
one might call “fantasy role playing”. If the role playing involved
M.C. performing a sexually suggestive physical act, then the
definition of “sexual service” might well be satisfied. However, in
the case at bar, M.C. took on the fantasy role of being the slave in a
master/slave relationship. M.C. did not perform any acts as a slave.
The “slave role” was one in the mind of the accused (and perhaps
M.C.), and had its expression in the content of emails and text
messages between Mr. Peterson and M.C., but M.C. did not engage in
physical acts for the sexual gratification of the accused. ...
[54] M.C. was cast in the
role of a slave in fantasy role playing, but the playing really only
occurred in the heads of Mr. Peterson and M.C. That does not
constitute the act of Mr. Peterson obtaining the sexual services of
M.C.
[citations removed]
But this was a lower trial court's reasoning that has not been adopted by others yet, and no other court has needed to develop the definition at the margins.