The notion that ministers of the Crown are collectively responsible for the policies of the government, and as such are obliged as individuals to stand or fall with decisions taken by the Cabinet as a whole, is not merely good advice, a matter of staying "on message." It is the very foundation on which another important constitutional convention, indeed the most important, rests: that of responsible government itself.

The public must know what are the policies of the government, and who is responsible for putting them into effect, if they are to hold the government to account. There cannot be several government policies on any given issue, each with its own standard bearer in Cabinet, nor can ministers dissociate themselves from the decisions or actions of their colleagues, as if it were no business of theirs. Well, they can, but then they must resign their office.

Which brings me to Sheila Copps. The Minister of Canadian Heritage has never been unduly constrained by convention, whether hurdling chairs in committee rooms or putting the squeeze on the Queen. But after her latest outburst, an unprecedented public attack on a fellow minister, even she must know she cannot remain in Cabinet.

Quite who appointed Ms. Copps as opposition health critic is a mystery. It isn't only that she is as yet a minister of the government, but that she has no conceivable responsibility for the matter on which she has chosen to enlighten us: SARS, and the government's handling of it.

Following last week's headline-making declaration that an outbreak confined to two or three Toronto hospitals was "an epidemic," indeed a "national emergency," Ms. Copps went on television Monday to vent her disappointment that the responsible federal minister, Anne McLellan, had not displayed the same sober judgment in her own approach to the issue.

"I think certainly the Minister of Health has some answering to do for the way that she has been absent from the file," she told CBC Newsworld. "Nobody saw her," she went on. "In the time when people were expecting to hear the strong voice of the government of Canada through the Health Minister, she was absent." Even in this government, where ministers routinely contradict one another on points of policy, this was breathtaking.

Now the issue here is not whether what she said was true or not. Nor is it the size of Ms. Copps's mouth, relative to her brain. The issue is: Who speaks for the government? Is it the considered opinion of Her Majesty's government, with Ms. Copps, that the Minister of Health has been "absent from the file," that she has shown no leadership in a "national emergency"? Or is the government's position, as Ms.

McLellan maintained, that Ms. Copps's characterization of events is "a huge overreaction," that the outbreak is "controlled and contained"? If it is the former, Ms. McLellan should plainly be forced to resign. If the latter, it is Ms. Copps who should go. The one position that is untenable is that both should remain in Cabinet.

Naturally, that is precisely the position taken by the Prime Minister.

"Mistakes are made once in a while, and they have been corrected," he shrugged after yesterday's Cabinet meeting. "Cabinet solidarity will be there and will remain there." Once again, Mr. Chretien shows his gift for creative interpretation.

There is no breach of Cabinet solidarity, so long as you interpret "solidarity" to mean the total absence of it -- just as earlier the convention of ministerial responsibility was defined to include the refusal of a minister to resign or otherwise take responsibility for his actions, or for those of officials in his department.

So we will have to guess at the government's position on the SARS outbreak. Does it maintain that everything was done at the federal level that could be done, and that the death of 21 people and a worldwide advisory against travel to Canada was not for any failure of policy or communication? Or should the Minister of Health be held to blame, at least on the latter count? The answer, it seems, is both -- conveniently so. Either position on its own would require somebody to stand up and be counted, whether to defend the government generally or to condemn Ms. McLellan individually. But as it is, the Minister of Health can be quietly hung out to dry, without the consequences that would ordinarily follow.

When you think about it, this is only the latest in a series of issues where the Chretien government has tried to have it both ways. Kyoto, Iraq and now missile defence: In every case it has been impossible to decipher what the government's position was, until it was too late -- and even then, the cloud of confusion lingered.

The Liberals used to say one thing and do another -- on the deficit, the GST, free trade, etc. -- sequentially. Now they do so simultaneously.