The Senate has once again amended Bill C-45, which will legalize cannabis for recreational use, setting up a potential showdown with the House of Commons over key provisions in the proposed legislation.

A Senate committee adopted 40 amendments to the bill this week, including a contentious one that would allow provinces such as Quebec and Manitoba to prohibit the home cultivation of cannabis.

On Friday, the Senate voted to prohibit any promotional material that is branded by cannabis producers, such as t-shirts and hats. The amendment was proposed by Conservative senator Judith Seidman, and it passed 34-28 with the support of 10 independent and unaffiliated senators.

The sponsor of Bill C-45 in the Senate, Tony Dean of the Independent Senate Group (ISG), said the restrictions on branding should have been dealt with through the regulations that will accompany the legislation.

However, the regulations have yet to be published. Conservative senators argue the government cannot be trusted to enact provisions that are strict enough and that is it better to adopt a more prohibitive bill.

“It’s better to make it narrower right now than to have to clean up a mess later,” Conservative Senator Leo Housakos said during the debate over the amendment.

There will be further debates on Bill C-45 between Monday and Wednesday, with daily themes, such as the impact of legalization on international affairs and the sanctions imposed for those who break the new law.

On Wednesday, the Senate will explore issues that affect Indigenous communities. In early May, the Senate committee on aboriginal peoples urged the federal government to delay legalization by a year to ensure the new regime meets the needs of Indigenous people.

The federal government has said it wants the legislation to come into effect this year. However, federal officials have refused so far to state exactly how they will respond to the amendments adopted by the Senate.

The bill will come to a final vote on Thursday, June 7, and it will then go back to the House of Commons, where the government will decide whether to reject the Senate’s amendments.

While he voted against the Conservative amendment on Friday, Mr. Dean said he is not concerned that it passed.

“The process is working as it should, and from the perspective of ISG senators, we are not voting as a block,” Mr. Dean said in an interview. “We are not a whipped group.”

He added he has not had any discussions with the government to gauge the reaction to the Senate’s amendments. If the House of Commons rejects some of the proposed changes, Bill C-45 will go back to the Senate.

“The government listens to the advice from the Senate, but not in every case,” he said. “The track record suggests they may accept some and reject others, but I simply don’t know.”

Lawyer Trina Fraser, who is monitoring the progress of Bill C-45 in the Senate, said it remains unknown whether the amendments adopted to this point will be palatable for the government.

“As it stands, I think this might be something the House could live with for the most part,” she said.

Still, she said that allowing provinces to prohibit home cultivation does not have unanimous support. Ms. Fraser added that the proposed ban on branded material has imposed a “greater stranglehold” on cannabis producers than the producers of alcohol.