10/21/2013 11:47 EDT | Updated 01/23/2014 06:58 EST

Mike Duffy's lawyer addresses Senate suspension

A lawyer representing Mike Duffy is expected to discuss key pieces of evidence in the senator's battle over expenses at a news conference in Ottawa today.

Duffy, in an email to CBC News, confirmed lawyer Donald Bayne will be addressing the media about legal issues in his case. will carry the news conference live at 12:15 p.m. ET.

On Thursday, the Senate gave notice of a motion that would cut the pay of senators Duffy, Patrick Brazeau and Pamela Wallin and bar them from the Senate chamber and Senate committee hearings. The motion, which accuses the senators of "gross negligence" is to be debated in the Senate Tuesday and put to a vote.

Duffy, Wallin and Brazeau were found by the Senate to have inappropriately claimed expense money following an independent audit of their travel and housing claims. All three have either voluntarily or have been forced to repay money to the Senate.

In Duffy's case, $90,000 was repaid even before the findings of the independent audit were made public by means of a cheque written by the prime minister's former chief of staff, Nigel Wright.

It's possible Bayne will say more Monday about the details of who in the Prime Minister's Office knew about that cheque, and perhaps any kind of paper trail related to the cheque Wright gave as a gift to Duffy. Prime Minister Stephen Harper has maintained he knew nothing of the payment until May 15.

Wright, who resigned as Harper's top aide, handed over a binder full of documents, including emails, to the RCMP, court documents reveal.

A lawyer for Wallin has complained about the Senate's intention to suspend her and cut her pay without any evidence that she committed gross negligence.

"They're [all senators who vote on the motion] constrained by the sense of due process under the charter, unless they say they don't care about due process and they don't care about the Charter of Rights, and that they can do what they want," said Terrence O'Sullivan on Friday.

However, Rob Walsh, the former top legal adviser to the House of Commons, said in an interview, that the Senate is not bound by considerations such as due process. "Due process, the right to hear the other side, the charter – none of that applies to parliamentary proceedings. But lawyers' first instincts are to invoke these principles they're accustomed to in legal proceedings."

Walsh believes the Senate does not have the power to cut a senator's sessional allowance, or pay, which he says is protected by the Parliament of Canada Act.