Updated, May 11: The Liberals in the House of Commons have indicated they will reject the Senate’s two latest amendments, sending the bill back to the Senate, however a vote won’t be held before May 22nd. 

The back-and-forth between the House of Commons and the Senate over Bill C-49 continues, as the Senate on Wednesday voted in favour of bringing back two amendments that the House of Commons rejected last week.

The 43-39 vote in favour of the amendments sends the transportation bill, which includes long-awaited changes for rail transportation, back to the House of Commons again. According to the CBC, it’s the first time since 2006 that the Senate has sent a bill back to the House a second time.

Saskatchewan Senator David Tkachuk brought forward the motion to re-introduce amendments related to final offer arbitration on rail rates and rail service in the Maritimes.

Farm and grain industry groups have been urging the government to pass the legislation as soon as possible — certainly before Parliament rises for summer so that the changes can be in effect for the start of the new crop year on August 1.

Both the House and Senate are not scheduled to sit next week.

It’s been an abnormally long and complicated path for C-49. Here’s our running timeline for keeping track of all the twists and turns along the way:

May 16, 2017 — Bill C-49 is introduced in the House of Commons by Transport Minister Marc Garneau. Farm and grain industry groups welcomed the legislation, as it contained some long-standing requests, such as giving shippers the right to impose reciprocal penalties for poor rail performance and granting increased power to the Canadian Transportation Agency.

May 24, 2017 — Garneau tells RealAgriculture he hopes to have the legislation in place by the end of 2017.

November 1, 2017 — C-49 passes third reading in the House of Commons, sending it to the Senate.

December 8, 2017 — It becomes evident the bill will not be passed before year-end, as the Senate transport committee begins reviewing C-49.

January and February, 2018 — Railway performance deteriorates, creating a grain backlog in Western Canada. Farm groups ramp up pressure on Parliament to pass C-49, with reciprocal penalty provisions.

March 29, 2018 — The Senate passes C-49, along with 19 amendments. The list of amendments includes several changes that were requested by farm and grain industry groups, such as: giving the Canadian Transportation Agency the ability to investigate rail performance without a formal complaint from a shipper; adjusting the long-haul interswitching provision to give elevators more access; and adding soybeans to the list of grains under the maximum revenue entitlement for railways.

April 27, 2018 — Transport Minister Marc Garneau introduces a motion to accept 10 of the Senate’s 19 amendments, including the main amendments lobbied for by the agriculture groups. The rejected amendments are largely unrelated to grain, pertaining to rail freight rate-setting mechanism that’s not usually used in agriculture, as well as airline investment, airline passenger rights, and transportation safety.

May 3, 2018 — The House of Commons approves Garneau’s motion, sending C-49 back to the Senate.

May 9, 2018 — Senators debate the changes and vote 43-39 in favour of bringing back two of the amendments that were rejected by the House of Commons, sending the bill back to the House a second time.

May 11, 2018 — Liberal MPs indicate they will reject the Senate’s latest amendments, sending it back to the Senate. However the House did not vote on the amendments prior to rising for a one week break; the earliest it can be sent back to the Senate is May 22.

June 2018 — The dates could change, but the House of Commons is currently scheduled to rise for summer on June 22, with the Senate calendar showing the last sitting day as June 29.

August 1, 2018 — Farm groups are adamant the legislation needs to be in place for the start of the 2018-19 crop year.

Related: C-49 taking the long route, headed back through the Senate