Those rules require that after a federal election, the MPs of each party hold a vote to determine the rules for caucus expulsions.
"We were expelled prior to the commencement of the Liberal caucus meeting", Philpott told the Commons from her new perch among independent MPs.
Had the caucus agreed at the start of this Parliament to put expulsions to a vote, last Tuesday's decision to remove the two women would've required 90 Liberal MPs voting in favour. Instead, Trudeau made the decision "unilaterally".
"These are basically new rules, just passed in the 41st Parliament in order to ensure that leaders didn't have so much power over their individual members", said May.
"The will of caucus was very clear, but I made the decision", Trudeau said.
Wilson-Raybould detailed the time last September when she told the PM himself he was acting inappropriately - an allegation Trudeau denied for weeks until, last week, he admitted to it under questioning in the House of Commons.
He has already ruled on a related question involving another former Liberal, Toronto-area MP Celina Caesar-Chavannes, who quit the Liberal caucus on her own in March, however.
Philpott asked the Speaker of the House of Commons to rule on whether the prime minister violated parliamentary privilege when he ejected the pair from the Liberal caucus last week, without holding a caucus vote on the matter.
Philpott said that left her, Wilson-Raybould and other MPs who might run afoul of Trudeau in the dark about how to fight an expulsion effort and how they might be readmitted to the Liberal caucus.More news: Burger King removes 'racist' advert of people eating burgers with chopsticks
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In that statement Scheer called Wilson-Raybould's submission "concrete evidence that proves Justin Trudeau led a campaign to politically interfere in SNC-Lavalin's criminal prosecution", and the entire affair "corruption on top of corruption on top of corruption".
Wilson-Raybould believes she was moved out of the prestigious justice portfolio to Veterans Affairs in a mid-January cabinet shuffle as punishment for refusing to override the director of public prosecutions, who had decided not to offer SNC-Lavalin a remediation agreement, a kind of plea bargain.
Two months later, Philpott declared she was stepping down, explaining that she had lost "confidence" in the government's solution of the case.
While that drama plays out in and around West Block, the Senate Open Caucus - which is "co-sponsored" by the Independent Senators Group, the Senate Liberals and the government's representative to the Senate - will tackle an issue that is, at least arguably, far more critical to the health and wellbeing of Canadians: "Anti-vaccine sentiment, and the "spread of disinformation on social media", which, according to the notice for today's session, "may be contributing" to Canada's comparatively low child vaccination rate", leaving "nearly one-tenth of children ... vulnerable to a host of potentially fatal, vaccine-preventable disease".
If that sounds nearly impossibly complicated, fear not: It very much is, particularly for the party now defending itself against a fresh wave of accusations that Prime Minister Justin Trudeau has violated the law of the land, which is what those same Liberal MPs - and, indeed, the prime minister - are virtually certain to face as they gather for their weekly closed-door confab - and, in Trudeau's case, when he takes his front-and-centre bench seat in the House of Commons later today.
Despite the best efforts of Liberals, the months-old SNC-Lavalin controversy keeps finding its way back to the headlines. "It was my decision to make but the fact that the caucus was clear and united on that made my decision easier".
Trudeau was unrepentant, arguing that with an election coming up, it's important that politicians be discouraged from twisting the truth and distorting reality.
Trudeau said Tuesday that despite there not being a formal vote, at the start of this Parliament the Liberal caucus did send a letter to the Speaker expressing the "will of caucus" in regards to these rules.
Justin Trudeau says we can't have politicians going around telling lies.