It's a legal argument. It could be used by someone...let's stay with the hypothetical we're talking about now. I emphasize that I'm addressing it as a hypothetical situation, where a minister is charged with interfering with a witness, of preventing a witness from attending before the committee. The minister's response and defence would be, “I did that with lawful excuse. My lawful excuse was the principle of parliamentary ministerial accountability, which enables me to direct that certain persons will not be available to the committee, and that I will be the one who is available.”
Would that be a legal argument that would prevail in court? My own thought is that it is an argument that should be made in the House, and the House should decide whether that's sufficient. If the House were to decide that it is not sufficient and the matter went to court, I think the court would be obliged to accept the House's determination. If in fact the House did not determine that question and it went to court, the court might say, “Sorry, we can't consider this matter; that's a matter of internal House proceedings and courts can't go there.” You have to think about those kinds of issues if you're looking at some extraparliamentary legal approach.
Generally speaking, with criminal offences, a person may have defences that we generically describe as lawful excuses. The emphasis is not on “excuse” but on “lawful”--exonerating circumstances that are recognized by law to have the effect of providing a defence.