At his History News blog, Christopher Moore is arguing that “responsible government is not a ‘convention’.” In his view, the “basis of responsible government in Canada” is right there in the constitutional text ― specifically, in the provisions of the Constitution Act, 1867 that deal with money votes. Dale Smith replies in a post at his own blog, Routine Proceedings, pointing out that these provisions make “no mention of a PM, or cabinet,” reflecting the fact that these are indeed the creatures of “the unwritten conventions that we inherited from the UK.” Mr. Smith has the better of this particular debate ― but his insistence that responsible government is purely conventional overlooks sources of constitutional law other than the text.
Mr. Moore claims that “Section 54 of the Constitution Act,  … sets out in plain language that only the cabinet can make and propose the raising and spending of money,” while “53 … bluntly states that only the House of Commons can give approval to the cabinet’s proposals for getting and spending.” He argues that “[s]ince getting and spending money covers everything a government does, these two sections make the government responsible to the Commons.” This is quite wrong.
First, the language of section 54 is anything but plain since, as Mr. Smith points out, it does not even mention the cabinet, and speaks of the Governor General instead. It convention that requires the Governor General to act on the cabinet’s advice. The constitutional text does not say that. Second, section 53 doesn’t say that “only the House of Commons can give approval” to money bills. It says that such bills must “originate in the House of Commons,” but they must, as all other bills, be approved by the Senate too. It is again convention that dictates that the Senate will not stand in the way of a money bill approved by the Commons. And third, one cannot simply equate the rules dealing with the passage of money bills with those of responsible government. For one thing, not only money bills are matters of confidence on which a cabinet will stand or fall ― so is the Speech from the Throne, and so can be other bills, if the government so chooses. And for another, there is no law of nature that says that money bills must be matters of confidence at all. In the United Kingdom, section 2 of the Fixed Term Parliaments Act 2011 means that they are not ― it takes a separate vote on a motion in prescribed terms for the House of Commons to express its lack of confidence in the government. It is, yet again, convention that (still) singles out votes on money bills as having a special constitutional importance in Canada. In short, while the text of the Constitution Act, 1867 was written with the conventions of responsible government in mind, it neither comes close to codifying them nor can otherwise be understood as “the basis of responsible government in Canada.”
That said, it is important to note, as Mr. Smith does not, that in Canada constitutional text is not all there is to constitutional law, and that it is possible ― and in my view likely ― that the rules of responsible government belong to that part of constitutional law which is not reflected in the text itself, and thus are not only conventional. In Ontario (Attorney General) v. OPSEU,  2 S.C.R. 2, Justice Beetz suggested that
[i]t may very well be that the principle of responsible government could, to the extent that it depends on … important royal powers [which may be entrenched by the references to the ‘offices’ of the Governor General and the Lieutenant-Governor], be entrenched to a substantial extent. (46)
More recently, and more importantly, in Reference re Senate Reform, 2014 SCC 32,  1 SCR 704, the Supreme Court took the view that the (legal) constitution encompassed, among other things, an “architecture,” consisting of “[t]he assumptions that underlie the text and the manner in which the constitutional provisions are intended to interact with one another.”  An interference with that architecture, the Court opined, amounted to a constitutional amendment. Now, the conventions of responsible government are surely among “the assumptions that underlie the text” of the Constitution Act, 1867, which concern “the manner in which the constitutional provisions are intended to interact with one another.” The text says nothing about the Cabinet, the Prime Minister, votes of confidence, or the Senate’s deference on money bills. But it would not have been enacted in its existing form had the existence of these institutions and rules not been assumed and universally accepted.
This leads me to the conclusion that, although the rules of responsible government are of clearly conventional origin, and the constitutional only leaves room for them to operate (in addition to referring to them, obliquely, in the preamble), they are now entrenched and legal rules. This is not to say that they are, or ought to be, justiciable. Perhaps courts would hold to the orthodoxy, expressed in the Patriation Reference,  1 SCR 753, that “the remedy for a breach of a convention does not lie with the courts,” (882) though I am not certain that they would. Yet just as a modification to the assumptions regarding the respective roles of the House of Commons and Senate requires, according to the Reference re Senate Reform, a constitutional amendment with provincial consent because it modifies the constitutional architecture (a view which the Supreme Court said “is supported by the language”  of the Constitution’s amending formula), so I believe would a attempt to change the rules of responsible government, say by limiting the scope of what counts as a vote of non-confidence. This would, in my view, be the case quite apart from any interference with the vice-regal office, though this may play the same sort of supporting role that the constitutional text played in Reference re Senate Reform.
I’d like to make one additional observation, regarding Mr. Smith’s claim that while
Responsible Government can function without [political] parties … in a theoretical world with vampires and unicorns, … it will never happen in real life. … The practice of parties developed for a reason. Maintaining confidence without them is a fool’s errand.
The conventions of responsible government gelled in the United Kingdom in the 1830s. There already were political parties by then, and there had been for quite some time. However, these parties were looser and much less disciplined than those to which we are used now. And they were indeed rather less good at maintaining confidence in the cabinet. The strong, disciplined, and effective parties that we know now emerged gradually, in response not only to the need for maintaining confidence but also to the broadening of the franchise which had only begun in 1832, and continued over the following decades. So while we almost certainly need political parties of some sort in order to maintain an effective system of responsible government, these parties need not look and operate the way they do today.