Prime Minister Justin Trudeau's bill legalizing recreational pot may have passed third reading in the Senate — but that doesn't mean its legislative journey will be a smooth or easy one from now on.

Senators made dozens of amendments to the government bill they sent back to the Commons Thursday night. Some of those amendments are likely to end up in the final bill. Others may not.

"We will have to go through the amendments. The minister will really provide information as to what amendments we are able to support, what amendments we're not able to support," said Liberal House Leader Bardish Chagger.

Actually, three ministers will be looking over the amended bill.

Public Safety Minister Ralph Goodale will look at changes in the legislation that affect policing. Health Minister Ginette Petitpas Taylor will consider amendments that touch on her portfolio and Justice Minister Jody Wilson-Raybould will examine the legal implications of the Red Chamber's proposed changes.

Some of those changes are minor tweaks, while others involve substantial alterations to the version of the bill that arrived in the Senate.

The Senate's social affairs committee, for example, passed an amendment that would leave rules on home cultivation up to the provinces to determine, allowing them to prohibit home-growing altogether.

That could affect Canadians living in Quebec and Manitoba, where the provincial governments already have said they want to ban home cultivation — a part of the bill the Liberals are anxious to keep.

"We set out a framework in C-45 that ensures safe access across the country to a legal source of cannabis and that includes home cultivation," Wilson-Raybould said Friday.

"We've been clear on our messaging in terms of the purpose of the legislation, and Bill C-45. But having said that, of course we are going to consider every amendment that the senators are putting back to us."

The amendment debate begins

Conservative Quebec Sen. Claude Carignan's amendment would establish a public registry of cannabis industry investors and directors to keep organized crime from finding a foothold in the legal marijuana business.

Liberal Quebec Sen. Serge Joyal passionately supported that move, saying many medical marijuana companies have been infiltrated already by criminal elements through offshore entities.



Under that amendment, a cannabis company's directors, officers, controlling parent corporations or trusts, and their directors, members and shareholders, would be listed in a public registry.

Critics of that proposed change say it raises serious privacy concerns because that level of public disclosure does not exist for other publicly traded companies.

A Conservative amendment that was supported by about a dozen independent senators calls for a ban on promotional items, or 'swag', that advertise cannabis. The amendment isn't clear on how far the ban would go, or how it would be enforced by police.

The government backed away from imposing a limit on the height of home-grown cannabis plants because it decided that enforcing the restriction would be overly cumbersome for police. That same criticism has been applied to the proposed swag ban.

'A very good piece of legislation'

Chagger said ministers will be working through the weekend to complete their review of the amended bill. After that, their recommendations on the Senate's version of the bill will be presented to cabinet for consideration. Then a motion will be drafted outlining which amendments the government can accept, which will be put before the Commons for a vote.

The House will send a message back to the Senate detailing which amendments it will adopt. If the Senate insists on amendments that the House has rejected, the upper chamber can then send the bill back to MPs.

This game of legislative ping pong can continue for a number of rounds — though typically one of the chambers eventually relents. In the event of an impasse, the two chambers of Parliament could delegate members to hold a rare face-to-face conference to settle their differences.

"I would think if we work overtime, like we've already been doing, that the earliest would probably be late Monday that we'd be able to put something on notice," Chagger said.

With Parliament's summer break fast approaching, the government is feeling pressure to move Bill C-45 along briskly — especially since the prevailing attitude in cabinet is that the government bill was in good shape before it went to the Senate.

"Bill C-45 ... when we brought it forward, we feel very confident that we had a very good piece of legislation," said Petitpas Taylor.

Once the motion on the final version of bill comes before the House, it will be debated before a vote is held. Each member can then speak to the motion, with time for questions on each speech.

If the government believes the Opposition plans to delay the bill through debate, it can limit the length of that debate through a procedural tool called time allocation.

"Mr. Scheer has been clear that on principle they oppose that legislation, so we know how they will be voting," Chagger said when asked if she planned to invoke time allocation.

"Hopefully they will endeavour to want to work better together, because they know how important it is for us to send a message back to the Senate as soon as possible."

Recreational pot won't be instantly legal once the bill passed both houses. As currently written, the bill stipulates the law does not come into force until a date fixed by an order of the governor-in-council — Trudeau's cabinet.

Full legalization is not expected until August at the earliest, as provinces have said they will need eight to 12 weeks of prep work before they can start selling the product to consumers.