The House of Commons justice committee is to begin hearings today into the allegation that the Prime Minister's Office improperly pressured former attorney general Jody Wilson-Raybould to help S-N-C-Lavalin avoid criminal prosecution.
Wilson-Raybould has been invited to testify, but likely won't appear until Monday.
She has repeatedly cited solicitor-client privilege to refuse comment on the allegation.
The Liberal-dominated committee wants to hear first from academics about the legal principles underpinning Wilson-Raybould's resignation from cabinet last week.
There will also be questions about the departure of Prime Minister Justin Trudeau's most trusted aide -- principal secretary Gerald Butts.
Opposition members maintain the hearings will be meaningless unless Trudeau waives solicitor-client privilege to allow Wilson-Raybould to speak freely.
They also want senior officials in his office, including Butts, called to testify.
M-Ps are also to vote on a non-binding N-D-P motion calling for a public inquiry into the affair and the waiving of solicitor-client privilege.