Is this the end of the Senate as we know it?

It was at 10:40 p.m. on Monday night, by a vote of 178 to 95, that the Senate was officially granted permission to remain in its current state for another year. With Conservatives and Liberals voting against, an NDP motion that would have withheld approval of $57 million in appropriations for the Senate—nearly two-thirds of the Senate’s budget for the next fiscal year—was thus defeated. Attempting to defund the Senate is a periodic tradition for New Democrats, dating apparently to 1921, when J.S. Woodsworth, future leader of the CCF, first attempted to have the House starve the Senate.

But the real threat to the Senate arrived 15 hours after Monday night’s vote, officially entitled “Report of the Auditor General of Canada to the Senate of Canada—Senators’ Expenses.” As a result of that 116-page audit, another nine senators—two current and seven former—have now had their expense claims forwarded to the RCMP for further investigation. Twenty-one other senators have been flagged for lesser concerns. In all, another $976,000 in questionable expenditures has been identified. This, after recent controversies had already diminished the Senate’s standing: criminal charges against Mike Duffy, Patrick Brazeau and Mac Harb and questions surrounding Pamela Wallin.

Related: Our coverage of the Mike Duffy trial so far

Meanwhile, the Senate’s membership dwindles as the Prime Minister refuses to fill vacancies and questions about the chamber’s future loom larger and more intimidating. Even for a chamber whose existence has been in dispute almost since its inception, the Senate’s current existential crisis is profound. Are we witnessing the slow-motion demise of the Senate? Or at least the end of the Senate as we know it?

“The weaknesses and problems uncovered in the course of this comprehensive audit of senators’ expenses call for a transformational change in the way expenses are claimed, managed, controlled and reviewed,” the auditor general’s office concludes in its report.

Under intense pressure back in 2013, after an expense scandal exploded with revelations of a secret payment to Mike Duffy from the Prime Minister’s chief of staff, the Senate invited auditor general Michael Ferguson to conduct a comprehensive audit. He looked at all expenses incurred by 116 senators from April 1, 2011, to March 31, 2013, examining more than 80,000 claims.

The issue of primary residence is a major point of dispute throughout the report. Ferguson documents numerous cases where his audit found senators were not mainly living where they claim to have their primary residences. Another issue is the mixing of personal business and parliamentary business when senators travel.

Related: Meet the 30 senators whose expenses are being questioned

“I think this is a good day for the Senate. Because I feel the air has been cleared,” said Conservative Sen. Doug Black, who was the first senator to begin posting details of his expenses online after he was appointed in 2013 (his expenses while chairman of the University of Calgary’s board had earlier been the subject of controversy). “I’m not of the view at all that this is a negative thing. I think that the greatest act of transparency was inviting the auditor general into the Senate. We now have his report and I am very, very pleased about the opportunity now to build on what he’s had to say.”

Some of the auditor general’s findings, however, are being challenged by the senators involved. Indeed, with details of the report leaked to the press prior to publication, senators were pleading their innocence before the precise details of their expenses had been revealed. “I am exploring my options for dealing with these adverse, baseless and unsubstantiated accusations,” said former Conservative senator Gerry St. Germain, whose file has been forwarded to the RCMP. “During my nearly 30 years of public service in Parliament, I always complied with all of the rules that governed the legislative bodies with which I sat.” Donald Oliver, another former Conservative whose file is with the RCMP, countered: “The conclusions drawn by the auditor are not based on all the facts. The claims of current concern to the auditor represented legitimate expenses incurred by me while doing Senate business.”

All 30 senators named by the auditor general can appeal his findings to former Supreme Court justice Ian Binnie, who the Senate has put in charge of an independent arbitration process. However those disputes are resolved, it could be years before the last of this scandal has been heard. Mike Duffy’s trial is now scheduled to run into the fall. The trials of suspended Sen. Patrick Brazeau and former senator Mac Harb have yet to begin. At last report, Pamela Wallin’s expense claims were still being investigated by the RCMP. And the auditor general’s findings raise the possibility of new charges and still more trials.

All of this investigation of the Senate’s internal management has also revived suggestions that the House of Commons should be reviewed as well. Such an audit could expand the expense scandal to those whose chances for re-election might depend on the results—investigations in recent years in the United Kingdom and Nova Scotia have roiled those respective legislatures, leading to resignations and criminal charges.

But the House is at least not burdened by questions about its inherent right to exist. The Senate has been so challenged for decades.

Though upper chambers at the provincial level were abolished years ago—Quebec’s was the last to disappear in 1968—many comparable democracies have the check and balance of bicameral legislatures at the national level, including Australia, the United Kingdom and Germany. But most other upper chambers are in some way elected—Canada’s Senate and Britain’s House of Lords existing as entirely appointed exceptions. Two years ago, a referendum in Ireland to abolish its senate was defeated by a vote of 51.7 per cent to 48.3 per cent. Famously conceived as a place of “sober second thought” to review legislation passed by the House, the Canadian Senate was also designed to balance regional representation at the federal level. Allotments of 24 seats are assigned to Ontario, Quebec, the Maritimes and the West.

The Library of Parliament traces attempts to substantially reform the Senate to at least 1874, but though some small changes have been made in the intervening years—whereas appointments used to be for life, senators currently must retire at the age of 75—the upper chamber has remained stubbornly unreformed in the midst of a lurching debate over its shape and purpose. While some insist senators must be elected and that a chamber of political appointees is outdated, even offensive, others argue for the advantages of an appointed review body free of electoral considerations, but still largely deferential to the elected House. (An elected upper chamber could lead to the sort of gridlock that currently plagues the American system.) A third option is outright abolition.

Related: A damning indictment—and a revolutionary fix?—for the Senate

The Conservatives were elected in 2006 with a promise to reform the upper chamber via elections and term limits, but did not move to impose those reforms once they gained a majority in 2011. Four rounds of non-binding Senate elections have been conducted in Alberta and Prime Minister Stephen Harper has put forward several of the winners of those votes in recent years. But since the Supreme Court ruled last year that moving to a fully elected Senate would require amending the Constitution with the consent of seven provinces representing at least 50 per cent of the population, and that abolishing the Senate would require unanimous consent of the provinces, the Harper government has seemingly abandoned all efforts toward substantial change. (It’s not clear whether any future attempts to conduct non-binding Senate elections would be constitutional.)

What’s more, Prime Minister Harper hasn’t nominated anyone for appointment to the Senate in more than two years. As a result, 20 of the Senate’s 105 seats are now vacant and two more senators are due to retire before this fall’s election. (Another three senators—Brazeau, Duffy and Wallin—are currently suspended.) But Harper has dismissed suggestions that he should fill any of those empty chairs. “I don’t think I’m getting a lot of calls from Canadians to name more senators right about now,” Harper joked last December. “I would just say that from the government standpoint, we’re able to continue to pass our legislation through the Senate, so from our standpoint, the Senate of Canada is continuing to fulfill its functions.” Inspired by those dismissive comments, Aniz Alani, a Vancouver lawyer, has applied to the Federal Court for a declaration that the Constitution Act requires that Senate vacancies be filled. The federal government is fighting Alani’s application, but even if the courts decline to intervene right now, it will not be possible to ignore the Senate forever. The upper chamber has a quorum of 15, Parliament requires a functioning Senate to pass legislation, and legal challenges could succeed if the Senate’s capacity is markedly impaired.

Related: Our politics podcast talks to Aniz Alani about his court application

For New Democrats, the answer is simple: the Senate must be abolished. But while that may be a useful rallying cry for a party that wants to “bring change in Ottawa,” as Leader Tom Mulcair says in the NDP’s latest TV ad, Quebec Premier Philippe Couillard has already said that if the Constitution is to be rewritten to remove the Senate, Quebec will want to make other changes as well.

The Liberals have the benefit of suggesting a practical change that likely doesn’t require federal-provincial negotiation. In January 2014, Justin Trudeau removed all Liberal senators from his parliamentary caucus and vowed a Liberal government would institute an independent selection process to suggest nominees for the Senate. That might create the sort of independent chamber, removed from the politics of the House, that the Senate is supposed to be, but it also requires justifying the existence of an unelected second chamber.

“It seems to me that if we’re going to go down the road of any profound change, we need to think about how come we have what we have,” says Liberal Sen. Joan Fraser, a former newspaper editor appointed to the chamber in 1998. “Believe me, I’m not saying that what we have is perfect. I’m absolutely not. But I’m a little concerned about facile calls for change. The Senate is an unheralded, but real part of the Parliament of Canada.”

There is something to be said for the mere existence of checks and balances—a second chamber does, or could, exist as a check on a majority government that would otherwise have its way with the House. The Senate’s capacity for study—Liberal senators promote the upper chamber as “Canada’s original think tank”—also arguably exceeds that of the election-minded House. Alberta Sen. Doug Black—who was appointed by Harper after he won a 2012 Senate nominee election—points to upcoming committee reports on energy development in the northern territories and crypto-currencies (such as Bitcoin). “The Senate and the senators, by far and away, do outstanding work,” he says, “which frankly has been clouded by all of the attention given, appropriately, to the review of our expenses.” Even those who seek the Senate’s abolition might need to explain how they would ensure that we would not end up missing it.

As is, the exercise of the Senate’s legislative mandate is a matter of some debate. The NDP howled in 2010 when the Senate defeated a bill on climate change and senators raised the ire of critics when it seemed they might amend Conservative MP Michael Chong’s Reform Act. An NDP MP’s bill on transgender rights was in the Senate for two years before a Senate committee moved to substantially amend it, while an NDP MP’s bill on sports betting has languished in the upper chamber since 2012. Though its studies may have influenced government legislation—a Senate committee recommended changes to the Fair Elections Act, some of which were accepted—it has been three years since the Senate actually sent a government bill back to the House with amendments.

“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,” Fraser says. “And at the moment, we have lost that, in my view.”

What might be necessary, amid the cries of outrage, the spectacle of legal proceedings and the politics of an election year, is actually something like sober second thought.

“It would be much better, in my view, to take a careful look at the institution that we have and say, among senators and among Canadians, okay, what should we do?” Fraser says. “Let’s go back to first principles and think about why we have one. Do the needs that it was originally set up to meet still exist or are there fresh needs that a Senate could serve? I would really like to see that conversation.”

—with files from John Geddes