[1] Parliament officially resumed on December 3, 2015, with the election of a new Speaker, Geoff Regan, followed by a Speech from the Throne the following day.

Among the more significant pieces of legislation adopted in the 42nd Parliament was Bill C-14, passed with a free vote, as the government's response to Carter v Canada; it inserted the term "medical assistance in dying" into the Criminal Code and made provisions for adult Canadians to engage in the practice.

[3] Bill C-16 added "gender identity or expression" to the list of prohibited grounds of discrimination in the Canadian Human Rights Act and the list of characteristics of identifiable groups protected from hate propaganda in the Criminal Code – with only 40 Conservative Party members, who were all granted a free vote, opposed the bill.

[8] In modernizing existing legislation, the Transportation Modernization Act (Bill C-49) amended the Canada Transportation Act to, among other things, implement long-haul interswitching as a permanent mechanism in the rail industry, exclude revenue from interswitching and from the movement of grain in containers on flatcars from Canadian National Railway and Canadian Pacific Railway's maximum revenue entitlement,; require railway companies to keep up-to-date plans for each of their railway lines and to publicly report on their abilities to move a given summer's grain crop along with a winter contingency plans, raise the foreign ownership limits for Canadian airlines from 25% to 49% of an airline's voting interest with the new rule that no single foreign investor may own more than 25%, expand the review of joint ventures in the airline industry to also include the public interest and fair competition practices; the bill also amended several other transportation-related acts including the CN Commercialization Act to increase the individual ownership limit in Canadian National Railway from 15% to 25%, and the Railway Safety Act to require the installation of locomotive voice and video recorders onto trains.

[15] On public safety and crime, Bill C-46 inserted new provisions into the Criminal Code regarding drug–impaired driving and the ability of peace officers to use drug screening equipment and random breath testing.

[17] Bill C-75, generally seeking to address court delays and promote fair and efficient trails but also included multiple other amendments, removed the allowance of peremptory challenge, allowed warrants to be acted upon anywhere in Canada rather than only in its originating province, added new provisions for videoconference by judges and court participants, restricted the use of preliminary inquiries to only cases involving offences punishable by life imprisonment, reclassified an additional 115 offenses as hybrid offenses so that they may be prosecuted either as summary convictions or as indictable offences, increased the maximum penalty for summary convictions to two years imprisonment, and deleted or amended offenses from the Criminal Code that the Supreme Court found to be unconstitutional (abortion in R v Morgentaler, vagrancy in R v Heywood, spreading false news in R v Zundel, anal intercourse in R v CM, and those offenses in R v Martineau).

[18] Bill C-51 repealed or modified provisions within the Criminal Code found to be unconstitutional or obsolete, including those against dueling, blasphemous libel, witchcraft, crime comics and trading stamps[19] and, in response to R v JA, clarified that an unconscious person is unable to grant consent to sexual activity.

[24] Partially in response to recent court decisions on solitary confinement and the recommendations of the Ashley Smith inquest, Bill C-83 replaced the system of administrative and disciplinary segregation in federal prisons with "structured intervention units".

[35][36] Bill C-62[37] restored or addressed changes made by the previous parliament to the Federal Public Sector Labour Relations Act regarding the determination of essential services, the ability to select between arbitration and conciliation to resolve collective bargaining disputes, and matters related to sick and disability leave.

Fulfilling a condition to ending Trump tariffs on steel and aluminum, Bill C-101 suspended, until 2021, the moratorium on trade safeguards.

[46] With only Liberal Party support, Bill C-7[47] was adopted as the government's response to the Supreme Court's ruling in Mounted Police Association of Ontario v Canada (Attorney General), allowing RCMP members to have certain collective bargaining rights.

[48] Bill C-58 amended the Access to Information Act to insert a new purpose statement, insert in requirements to make requests, allow bad faith or vexatious requests to be refused, and require proactive publication of certain information (e.g. travel expenses, hospitality expenses, etc.

The Canadian Forces disability award and death benefit were raised to $360,000; the rates for Northern Residents Deduction were increased by 33%; and employment insurance benefits were temporarily extended for high unemployment areas (e.g. the northern areas of the provinces of Ontario, Manitoba, Saskatchewan and BC, the cities of Sudbury and Whitehorse, and most of the provinces of Alberta and Newfoundland and Labrador).

[63] Among the changes was making cannabis subject to an excise duty, requiring the excise duty on tobacco products be adjusted for inflation every year instead of every five years, reducing the small business tax rate from 10.5% to and to 9%,[64] removing the requirement for a risk score to Canadian Armed Forces personnel and police officers serving on international missions to qualify for tax relief on income earned while deployed, amending the Veterans Well-being Act to merge four benefit programs to create the new Income Replacement Benefit and replacing the Disability Award with a new 'pain and suffering compensation', renaming the 'Working Income Tax Benefit' to the 'Canada Workers Benefit' while increasing its rate from 25% to 26%, expanding the Medical Expense Tax Credit to cover the costs of caring for a service animal benefiting those living with a severe mental impairment,[65] extending the Mineral Exploration Tax Credit by one year, extending the accelerated capital cost allowance program for clean energy generation and energy conservation equipment to 2025, expanding who is subject to Tax-on-Split-Income rules,[66] creates the office of the Chief Information Officer of Canada, extends the provincial equalization payments program to 2024, and inserted provisions for deferred prosecution agreements into the Criminal Code.

Among the changes was the creation of the Canada Training Credit and the Digital News Subscription Tax Credit, a 5-year extension of the Mineral Exploration Tax Credit, financial incentives for purchasing specified clean energy equipment and zero-emissions vehicles, exempting GST/HST from applying to supplies and imports of human ova and imports of human in vitro embryos, allowing non-profit news organizations to issue charitable receipts, eliminating the requirement to complete an application to enroll into the Canada Pension Plan, allowing recipients of the Old Age Security to earn $5,000 of income without deductions, creating a First-Time Home Buyer Incentive administered by CHMC, creating a six-month interest-free period on student loans, and redirecting revenue raised from carbon pricing to the areas where it was raised.

Non-financial or business related amendments within Bill C-97 include a modernization of the Pilotage Act, increasing the number of judges on the Federal Court, making a provision which prevents people from making a refugee claim if they have already made a refugee claim in another country and inserting the Thaidene Nëné National Park Reserve into the Canada National Parks Act.

Other Senate public bills included the Justice for Victims of Corrupt Foreign Officials Act (Sergei Magnitsky Law)[94] which allows the Governor-in-Council to seize property situated in Canada of a foreign national believed to be involved in extrajudicial killings or violations of internationally recognized human rights, and the Journalistic Sources Protection Act (Bill S-231)[95] which allows journalists to object to an order to reveal a source of information and have the objection weighed by a court judge in light of public interest and rights to privacy.

Bill Blair had the Ministry of Border Security and Organized Crime Reduction created for him from duties split off of Ahmed Hussen's portfolio.

A shuffle on January 14, 2019, instigated by the resignation of Scott Brison, President of the Treasury Board, saw Jane Philpott move from Minister of Indigenous Services to replace Brison, with Seamus O'Regan filling her former position and Jody Wilson-Raybould replacing him as Minister of Veterans Affairs.

[99] Amidst the SNC-Lavalin affair Wilson-Raybould and Philpott resigned their cabinet positions and were replaced by Lawrence MacAulay and Joyce Murray, respectively, with Marie-Claude Bibeau taking over MacAulay's former role as Minister of Agriculture and Maryam Monsef adding Bibeau's International Development duties to her existing duties as Minister of Status of Women.

Based on their first set of recommendations, Premier Trudeau appointed 6 new senators in April, including chairman of the Truth and Reconciliation Commission Murray Sinclair, former NDP provincial minister Frances Lankin, journalist André Pratte, Paralympian Chantal Petitclerc, and academics Raymonde Gagné and Ratna Omidvar.

These senators included Éric Forest, bankers Sabi Marwah and Lucie Moncion, police commissioner Gwen Boniface, academics or doctors Yuen Pau Woo, Wanda Thomas Bernard, Diane Griffin, Marie-Françoise Mégie, Harvey Chochinov, art historian Patricia Bovey, lawyers Marilou McPhedran, Renée Dupuis, Marc Gold, former public servants Tony Dean, Howard Wetston, Raymonde Saint-Germain, and artist René Cormier.

Throughout 2018, a further 19 senators were appointed, all of whom caucused with the Independent Senators Group, including teacher Marty Deacon, lawyers Yvonne Boyer, Pierre Dalphond and Josée Forest-Niesing, doctor Mohamed-Iqbal Ravalia, interim RCMP Commissioner Bev Busson, journalists Paula Simons and Julie Miville-Dechêne, and former Yukon Premier Pat Duncan.

Senate House of Commons Senate House of Commons Senate House of Commons Access to Information, Privacy and Ethics Agriculture and Agri-Food Canadian Heritage Citizenship and Immigration Environment and Sustainable Development Finance Fisheries and Oceans Foreign Affairs and International Development Government Operations and Estimates Health Human Resources, Skills and Social Development and the Status of Persons with Disabilities Indigenous and Northern Affairs Industry, Science and Technology International Trade Justice and Human Rights National Defence Natural Resources Official Languages Procedure and House Affairs Public Accounts Public Safety and National Security Status of Women Transport, Infrastructure and Communities Veterans Affairs Joint Committee on the Library of Parliament Joint Committee for the Scrutiny of Regulations Electoral Reform Pay Equity Joint Committee on Physician-Assisted Dying The party standings in the House of Commons have changed as follows: The party standings in the Senate have changed during the 42nd Canadian Parliament as follows: Bold indicates parties with members elected to the House of Commons.