“At the end of the day, we will not be judged on how efficiently we manage our budget, but on how effective we are as a legislative body,” Sen. James Cowan ventured this week, moments before the Senate concluded what was surely one of the least flattering terms in its history. “Review of legislation is our principal role and, the better we do that job, the more respect we will gain from Canadians. Do that job poorly, as we have many times, and we will not gain—much less deserve—that respect.”

Imagine this spring unfolding for the Senate as it did, but with one difference: Instead of passing Bill C-51, the government’s anti-terror act, unamended on June 9, imagine the Senate had amended the bill and sent it back to the House for consideration. Imagine, for the sake of this thought experiment, that a majority of senators had insisted on writing a sunset clause into the bill (as Senate Liberals proposed).

Conservatives in the House might have howled about unelected and unaccountable senators thwarting the democratic will, perhaps even endangering the nation in the process, or some such. And New Democrats might have still lamented the Senate’s refusal to defeat the bill. But New Democrats also might have at least been asked to concede that the upper chamber had gone further in amending the bill than the House. The Harper government would have been compelled to either accept the changes or justify refusing to amend an unpopular bill. The Senate’s legitimacy might have been questioned, but, in exercising its power, the chamber might have reminded everyone why it exists.

It would have been the first time in three years that the Senate has sent an amended bill back to the House (in that case three years ago the government was merely amending its own bill after realizing too late that amendments proposed by Liberal MP Irwin Cotler were, in fact, prudent).

Instead, C-51 passed with only an “observation” that it be studied by a Senate committee in five years, and that second week of June was dominated entirely by the Senate expense scandal.

That scandal is not trivial. It will stain the Senate for years. But it is also tangential to the real questions about the Senate’s continued existence. Ideally, its members would not be filing inappropriate expenses. But even a Senate of the perfectly frugal and demure would still have to answer the same questions about its precise utility.

Even while C-51 passed without amendment by the Senate, the upper chamber had at least one other high-profile opportunity to demonstrate independent authority before adjourning for the summer: It might have amended or defeated C-377, the controversial bill on union disclosure. Union leaders would have been happy to see the Senate so assert itself. Instead, C-377 passed, and with Conservative senators voting to overrule the Speaker to compel the bill’s passage.

“That defence—that, on occasion, the Senate will stand up and do the right thing by opposing something which is clearly impractical, not workable, unconstitutional and negative in its impact on important things like the role of collective bargaining in a free and open, competitive economy—that defence is now gone,” former Conservative senator Hugh Segal subsequently told the Canadian Press. “So, whatever the defences were for the continuing existence of the institution and its relevance . . . those who voted against the Speaker have just cut a huge hole in that flag.”

For all the visceral intrigue of the Mike Duffy affair and the other expense-related revelations, the most unbecoming revelation of these last four years for the Senate remains what the RCMP uncovered about how the Prime Minister’s Office had apparently directed the rewriting of a Senate committee’s report on Duffy. Among the RCMP’s discoveries was a March 2013 memo to the Prime Minister detailing his office’s new efforts to manage the Senate (and his staff’s shock at how independently senators had been acting).

This should be considered a far greater threat to the Senate’s credibility. That senators are accused of making inappropriate expense claims might impugn the ethics of some members of the upper chamber, but that the PMO would be able to easily manage Senate business is a threat to the very idea of a Senate.

Even if the Senate is deeply problematic in practice and design—a chamber of unelected legislators, appointed entirely at the discretion of the Prime Minister, its members including party loyalists and fundraisers—there is notional value in the idea of checks and balances, and the check and balance that a second chamber could provide.

It would seem to be the current view of the Prime Minister that the Senate exists only to pass government legislation—or, at least, that is the basis for his refusal to fill the 20 vacancies in the chamber. But that’s really only an argument for abolition. If the Prime Minister only views the Senate as a formality, he should ask his excess appointees—the Conservatives could currently lose a dozen senators and still hold a majority—to quit.

Stephen Harper did once say that he saw some value in “sober and effective second thought” and giving “voice to our diverse regions.” He just wanted the Senate to have “democratic legitimacy.” There’s certainly something to be said for democracy, and something reflexively objectionable about an upper chamber of political appointees that reviews legislation passed by a democratically elected House. (If we were starting over from scratch tomorrow, is there any chance we’d design a system with a chamber of the Prime Minister’s appointees?) But then, it’s not clear how much can be said for the democratically legitimate lower chamber we do have. And so it might thus be doubly unclear why we’d replicate it. An elected Senate might be more legitimate than an appointed Senate, but what else? Would it be more useful somehow? Or would it simply be a second version of our much-maligned House, dominated by partisanship and the constant pursuit of electoral advantage? And if the government can mostly have its way with an elected House, why wouldn’t it be able to have its way with an elected Senate?

That the current House might not act as an effective check on the government is actually the best argument for maintaining a second chamber. It might even be the best argument for maintaining an appointed Senate. But then, there’s something unfortunate about any argument that depends on agreeing that the House can’t provide sufficient accountability. And it remains unclear how well the Senate is currently acting as a check on power.

Eventually, we arrive at a riddle: The best argument in favour of the Senate is the House of Commons. And the best argument against the Senate is the Senate.

“My own belief is that, where we are failing in our duty is that we are not being independent, we are not standing up and amending legislation that needs to be amended, whether it’s government legislation or private members’ bills,” Liberal Sen. Joan Fraser told me last month. “If you’re going to have a Senate, if you’re going to have a Senate with job security for a long time, without the need to be re-elected, the advantage of that has to be that those people can exercise independent judgment and vote according to their conscience without fear. And, at the moment, we have lost that, in my view.”

Independence is hard to quantify, but we can at least count how often the Senate imposes its opinions on bills passed by the House. In the four years of this 41st Parliament, senators sent just two bills back to the House of Commons. (One of those bills was C-377, but a subsequent prorogation wiped out the Senate’s amendments.) That’s the lowest tally for a Senate since the 32nd Parliament. During the three Parliaments from 1993 to 2004, when the Liberals had a majority in the House, the Senate amended 14, 10 and 14 bills, respectively. In the two Parliaments of Conservative majorities in the House from 1984 to 1993, the Senate amended a total of 26 bills.

There is at least one possible caveat here: the partisan balance of power in the Senate. It’s not clear to me when, precisely, the majority in the Senate has switched from one party to the other in the past, but, owing to the tendency of prime ministers to appoint senators from their own party, the Brian Mulroney government took office with a Liberal majority in the Senate and the Jean Chrétien government then took office with a Conservative majority in the upper chamber. Harper, on the other hand, had built a Conservative majority in the Senate by 2010, a year before he gained a majority in the House.

There is also the Senate’s habit of performing “pre-studies“: Committees of the upper chamber sometimes study bills before the legislation has been passed by the House, allowing, conceivably, for changes before the bill reaches the Senate. Senators could, for instance, claim to have influenced government amendments to the Fair Elections Act. (Off the top of my head, I wonder whether the Senate’s review function would be better served by avoiding pre-studies.)

Mind you, an assessment of the Senate’s legislative record can’t be limited to government bills. The proliferation of private members’ bills is raising questions that go beyond the Senate, but there are complaints that the Senate adjourned this week without passing C-518 (dealing with the pensions of MPs and senators) or C-290 (sports betting), and C-279 (transgender rights) languished after being amended by a Senate committee. Last year, the Senate approved a private member’s bill with known errors (though that reflects poorly on both chambers). Five years ago, the New Democrats howled when the Senate simply killed an NDP bill on climate change.

Conservative Sen. Doug Black, appointed by Harper after winning a Senate election in 2012, believes the Senate functions with independence—”Any suggestion that we take instructions from the PMO, or the PMO is in regular contact with regular, run-of-the-mill senators like myself, just is not on”—and argues that some of the Senate’s work in suggesting changes is done quietly, with official suggestions and in private discussions.

“We work quietly, we work discreetly, and we are very conscious that we are not the elected chamber,” he says. “So we need to be respectful of that reality.”

Therein lies the other conundrum (neatly captured here): It thwarts the will of the people when it acts to block a bill, but it seems useless when it allows a controversial bill to pass without amendment. That is not easily solved.

At best, the Senate might be judged on the merits of the amendments it makes, but, of course, one’s judgement of that will tend to depend on one’s political allegiance. And perhaps the Senate has to be particularly mindful of public opinion at this particular moment; it is not currently a chamber blessed with ample credibility.

If the 42nd Parliament involves an NDP or Liberal government, the Senate, with its Conservative majority, might suddenly rediscover its assertiveness. With a reformed appointment process, as the Liberals propose, the upper chamber might also gain credibility, or, at least, prove more difficult to control. The argument for abolition could, in theory, be hurt by the Senate’s intervention against an unpopular or problematic bill, or it could be greatly helped by a display of simple partisan obstruction.

For now, abolitionists like the NDP might at least be asked to explain why the House is sufficient on its own. Whatever the meals that have been expensed and the mechanics of constitutional reform, the precise utility of the upper chamber is still the primary question.

None of this is necessarily new. The Senate’s existential crisis is possibly as old as the Senate. But it’s that existential crisis that the expense scandal should lead back to. It is not so much whether or not a senator should be able to claim his cottage as his primary residence, but whether or not there should be such a thing as a senator at all and, if so, how?