The Senate has concluded its committee study of Bill C-36 and the bill is expected to be back before the upper chamber for third reading next week.
Liberal Sen. George Baker said Thursday he intends to introduce 15 amendments during that debate, all seeking to remove provisions which would criminalize those who sell sex.
"We didn't hear from anybody who said that those provisions should be there," he said in an interview.
The Conservative government wants to get the bill through the legislative process by the middle of November, so it can get royal assent and become law by December. That would meet the deadline imposed by the Supreme Court of Canada when it struck down existing laws as unconstitutional last year.
The court found the laws violated the charter rights of sex workers because they were criminally prohibited from taking measures to keep themselves safe.
In response, the government introduced the current bill, which it argues protects sex workers by giving them access to bodyguards and the ability to work indoors.
However, none of that can happen if a third party benefits or the sex worker is operating in exploitative conditions.
But scores of witnesses told both MPs and senators that the various exemptions in the bill are open to further charter challenges.
For example, while the bill would allow sex workers to advertise, it would make it an offence for anyone to run those ads, said Ian Clark, an executive member of the Canadian Bar Association's national criminal justice section.
"Therefore, an individual who is attempting to sell their services cannot avail themselves of any advertising, can't screen clients on the Internet, various things that the Supreme Court raised that were important," Clark told the Senate legal affairs committee on Thursday.
"This ban on advertising, given the fact that selling remains lawful, is potentially unconstitutional."
The bill has already been amended once, to tighten restrictions on where it would be illegal to communicate for the purpose of selling sex.
But that provision, as well as any others which continue to criminalize sex work need to be struck out, Baker said.
He said he was troubled by testimony from Manitoba's provincial justice minister, who said he would simply tell prosecutors not to proceed with charges in the event prostitutes were arrested under those provisions.
That creates an abuse of process, which is a constitutional violation, Baker said.
"You'll have somebody arrested, put in jail probably and then no prosecution taking place," he said.
"So it's a rather ridiculous situation that those provisions are now in the bill that will create such confusion at the end of the day."
For Baker's amendments to pass, he'll need the support of some Conservative senators as their party holds the majority in the Senate.
"I think there will be some support there simply because it's a unanimous thing on the part of those who have appeared," he said.
Debate over the bill has revealed a split between those who consider sex work a legitimate profession that requires access to safe working conditions and those who see all people working as prostitutes as victims in an industry that needs to be outlawed.
But the Senate committee was urged Thursday to consider putting partisan differences aside to reach a compromise on good legislation to protect everyone.