Last week, Bill C-14 landed in the Senate. The legislation clarifies the law for doctor-assisted suicide following a 2015 Supreme Court ruling that struck down the barriers to it.

Both Conservative and independent Liberal senators say they want changes to C-14, which excludes three measures recommended by the special committee that initially studied the issue. The Liberal government says it's open to amendments, but rejected most changes when the House of Commons committee studied the bill.

If the two houses of Parliament can’t agree on the final text of a bill, it can ping-pong between the chambers until they reconcile their positions.

If the two can't come to an agreement – for example, if the Senate amends the bill, the House refuses to accept the amendments and the Senate won't budge – that could trigger a conference between the two houses of Parliament. The last conference was held in 1947, and they were rare even before then. It's been so long since the last one that it's likely anyone involved is no longer alive.

"This practice has fallen into disuse and has been replaced with frequent communications between the two Houses by way of official 'messages' and the appearance of Ministers before House and Senate committees," according to an October, 2015 article about procedure on the parliamentary website.

Last week, for example, Health Minister Jane Philpott and Justice Minister Jody Wilson-Raybould appeared before the Senate for several hours to take questions about the bill.

Still, conferencing "is nevertheless held in reserve in case of a deadlock in connection with Senate amendments to a bill," according to the O'Brien and Bosc House of Commons Procedure and Practice, the book that is essentially the parliamentary Bible.

Given the sensitivity and complexity of the assisted-dying legislation, it’s possible Parliament will see conferencing resurrected – though the Liberal government won’t say whether they’re considering the possibility.

"At this point, it would be premature to discuss the potential disposal of Senate amendments, which may or may not take place, before the government formally receives them," Sabrina Atwal, a spokeswoman for Government House Leader Dominic LeBlanc, said in an email to CTV News.

How it works:

  • In a conference, an MP sends a message to the Senate to request a meeting.
  • The Senate suggests a time and place, and selects "managers" to represent it.
  • The House selects its own managers, usually including the minister who sponsored the bill.
  • Those managers go to the Senate at the designated time, the Senate managers leave with them, and the conference begins.

"Since no official report or minutes were prepared for those conferences, there is very little information available as to how free conferences were held in the past and on who attended them in addition to the managers from the two Houses," says the entry in O'Brien and Bosc.

Once they reach agreement, one of the House managers reports back to the House. MPs vote on the report and the House sends a message back to the Senate about the result.

C-14 has already had an unusual treatment in the Senate. After a pre-study and another day of consideration by the legal and constitutional affairs committee, the committee referred the bill back to the full Senate before considering amendments. That means all senators will have the chance to vote on as many as 50 expected proposed changes. The debate on those changes is likely to happen on Wednesday.

If the bill is amended, it will go back to the House for those amendments to be debated. The House needs 24-hours notice before it can start that debate.

The House can accept, reject or amend the Senate's amendments, and then send the bill back to the Senate. This continues until the bill is passed.

"If there's an impasse it just goes on. It just goes on and on and on," said independent Liberal Senator George Baker. "So that's the uncharted territory we're embarking upon."

If the two chambers can't agree, the bill sits on the order paper until prorogation, at which point it dies.