Terrence O'Sullivan said, "This matter is not over by any stretch of the imagination."
The Senate voted Tuesday to suspend Wallin and senators Mike Duffy and Patrick Brazeau without pay for making inappropriate housing and travel claims.
The three senators, along with Mac Harb, who recently retired from the Senate, are being investigated by the RCMP.
CBC News has learned that at least one of the senator's files, if not more, has been handed over to provincial Crown attorney Brian Holowka.
It's up to the Crown to decide if there is enough evidence to proceed with criminal charges. It’s not known how long that process might take.
O’Sullivan pointed out that many senators "tried to do the right thing" as they prepared to vote on the suspension of his client, but were "bullied" by the prime minister and the Prime Minister's Office for reasons of "political expediency."
O'Sullivan complained about the lack of due process in Wallin's case.
Ex police chief defends suspensions
Conservative Senator Vern White told Robyn Bresnahan, host of CBC Radio's Ottawa Morning, he wanted to get rid of a "few senators" since last spring, when the allegations against Duffy, Wallin, Brazeau and Harb became public.
White, a former Ottawa police chief, said suspensions without pay are sanctions that can happen in most police forces, except in Ontario.
All other police forces in Canada, he said, can suspend an officer without pay even if there is no criminal conviction.
White said one of the tests for suspension of police employees without pay is that "the public would be outraged that you continue to receive money from the public purse based on the actions you are purported to have committed.
“Not convicted of, purported to have committed," he repeated.
"I've probably been the most outspoken about this," he told Bresnahan, seemingly referring to his conversations with other senators. "Last spring I said I'm concerned about the fact that for some loyalty is more important than integrity, and I think that all of them would have realized that to me this is an integrity issue."
This is not "a rules problem," he added, alluding to the fact some senators say the expense claim rules are ambiguous.
Will senators' staffers lose jobs?
It's not clear if the three senators’ suspensions mean that their staff members will lose their jobs. Some employees who work for senators are employed by the Senate, and can be shuffled around if they leave a senators' office.
Debby Simms, who works for Brazeau, told CBC News she is meeting with the Senate human resources department Wednesday and has already been told she has two weeks to clean out her office and hand over office equipment, including her parliamentary pass and her BlackBerry.
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