The best answer there is to actually look at section 139, where it sets out what's required in terms of the “evidentiary burden”, as you call it. In any criminal offence, of course, you have to prove the person did the deed that is prohibited by the Criminal Code provision.
This provision, in section 139, provides that
Every one who wilfully
—I'll come back to that in a minute—
attempts in any manner to obstruct, pervert or defeat the course of justice in a judicial proceeding,
—and it sets out two possibilities—
by indemnifying or agreeing to indemnify a surety, in any way and either in whole or in part, or
That's subsection 139(1), which really doesn't apply to the situation we're dealing with.
I should read subsection 139(2):
Every one who wilfully attempts in any manner other than a manner described in subsection (1)
—because that deals with sureties—
to obstruct, pervert or defeat the course of justice is guilty of an indictable offence and liable to imprisonment for a term not exceeding ten years.
And then subsection 139(3) goes on to offer some illustrations of what that means. It says:
every one shall be deemed wilfully to attempt to obstruct, pervert or defeat the course of justice who in a judicial proceeding,
—which, by the way, is defined in the Criminal Code as including a committee proceeding—
existing or proposed,
(a) dissuades or attempts to dissuade a person by threats, bribes or other corrupt means from giving evidence;
(b) influences or attempts to influence by threats, bribes or other corrupt means a person in his conduct as a juror; or
—that doesn't apply here—
(c) accepts or obtains, agrees to accept or attempts to obtain a bribe or other corrupt consideration to abstain from giving evidence, or to do or to refrain from doing anything as a juror.
As a matter of interpretation, one of the problems the language suggests to you is that when it says “threats, bribes or other corrupt means”, you have to be thinking in terms of corrupt threats, corrupt bribes—bribes by definition are corrupt, I suppose—or other corrupt means, as opposed to a conversation that might take place where remarks are made to the witness about whether he or she should think twice about attending. These kinds of remarks may be characterized—“may”, I'm saying—as not being corrupt.
But the further evidentiary problem goes back to the use of the word “wilfully”. Were those remarks made with the intention of trying to prevent the person from appearing in front of the committee? Those are the evidentiary burdens. You have to prove them. You have to prove, in my view, the corrupt nature of the interference and that it was wilfully intended to interfere, as opposed to some remark made in passing that, taken out of context, would not support that kind of charge.