The Senate may have have no choice but to suspend any current senators flagged by the auditor general for improper spending because that's what was done to Mike Duffy, Pamela Wallin and Patrick Brazeau, some legal experts say.

Auditor General Michael Ferguson is to submit his audit of every senator in the first week of June, and CBC News has already reported that the expenses of between five and 10 senators have been flagged with having serious problems.

The question now is how to deal with them. And whether suspension without pay is the precedent that has been set.

"I think they should be treated the same way as Duffy, Wallin and Brazeau," says University of Ottawa law professor Pierre Thibault.

He says that would not only be a matter of consistency and fairness, but it would show taxpayers that their money will be protected.

Treating anyone differently, after being flagged by the auditor general for serious spending problems, would suggest preferential treatment, he adds.

"That would send a wrong message to Canadians. Don't forget senators are using public money and we should be very careful when we spend public money.''

Independent arbiter?

Just what the Conservative leadership in the Senate is thinking about this isn't at all clear.

The new Senate speaker, Conservative Leo Housakos, suggested to one reporter that an independent arbitrator would determine any punishment.

Now, the government's leader in the Senate, Claude Carignan, tells CBC News that suspension without pay remains an option, but he's not committing to it.

"Look, yes. If we have other bad behaviour we are willing to continue to discipline our senators," Carignan said. "We have a new code of conduct now and we could use the ethics commissioner to investigate and recommend a disciplinary sanction."

Senator Claude Carignan, leader of government in the Senate, speaks to the media on Parliament Hill in November 2013 after senators voted to suspend colleagues Patrick Brazeau, Mike Duffy and Pamela Wallin for allegedly claiming improper living and travel expenses. (The Canadian Press)

There was no such intermediate step for Duffy, Brazeau and Wallin.

Rob Walsh, the retired law clerk of the House of Commons, also said that giving different treatment to anyone else flagged with spending irregularities raises its own set of problems.

"How do you justify it? The onus is on you to explain why you are choosing to do it differently and that would be a difficult thing to explain given what you did before."

Liberal Senator James Cowan agrees the Senate is in an awkward position on this matter.

He said the suspensions of Duffy, Wallin and Brazeau didn't follow the normal practice of waiting for a police investigation to finish and for criminal charges, if any, to be laid before taking disciplinary action.

"What I objected to in the case was that the government was making up procedures in order to deal with particular cases," Cowan said. "That's exactly the wrong way to go about doing things, and that's the reason we are in the kind of mess we are now.''

Cowan says the choice now is for the Senate either to repeat the same practice or to change the process and open itself up to accusations that the previous suspensions were for purely political reasons.

"I'm sure that no matter what the Senate does, when it does it there will be people who will say 'you should have done something else'."

Walsh agrees that the Senate is in a bind, if it doesn't move to suspend any senator identified by the auditor general of serious financial irregularities.

"How much of what the Senate is going to do is going to serve the public interest or serve the Senate's interest. And that's going to be the issue.''