Mallard had had a reputation as an "attack dog" and "political battler" (he was once convicted of fighting in a public place after punching National MP Tau Henare at Parliament).

[2][3][4] His speakership was remarked on for its contribution to parliamentary culture change, including promoting a more family-friendly environment and removing the requirement for male MPs to wear ties.

[16] He was arrested for disorderly behaviour outside the Springbok rugby team's Rotorua hotel during protests against their 1981 tour of New Zealand, but was found not guilty.

[20] He held a number of internal party positions until the election of 1984 when he defeated Mike Minogue to become the member of Parliament for Hamilton West.

After his election loss, Mallard returned to the Wellington area to live and work at parliament as an executive assistant to Mike Moore in the office of the Leader of the Opposition.

He then contested the Labour Party nomination in the seat of Pencarrow after Sonja Davies announced her retirement, winning the selection over Eastbourne-based polytechnic lecturer Tricia Thompson.

The electorate was renamed Hutt South in 1996, and Mallard retained the seat until 2017 when he opted to become a list MP in a bid to become the Speaker of the House.

[27] Clark appointed Mallard to spokesperson roles in portfolios for which he would later hold ministerial responsibility, including sport, state services, and education.

Mallard pleaded guilty to fighting in a public place and agreed to pay $500 to the Salvation Army's Bridge drug and alcohol programme.

[38] In 2006, Mallard announced that the government would introduce a policy that encouraged state-owned enterprises (SOEs) to expand into new business areas and diversify in order to build wealth for the country.

The announcement was made following a number of incidents by SOEs, including a power disconnection by Mercury Energy that resulted in the death of Folole Muliaga, an individual who relied on an oxygen machine.

[46] In December 2019, former Auditor-General Martin Matthews claimed that Mallard and other members of the Officers of Parliament committee, including then-Speaker David Carter, had pressured him to resign prior to the release of a critical report by Sir Martin Wevers into Matthews' handling of a NZ$725,000 fraud perpetrated by Ministry of Transport employee Joanne Harrison.

Matthews claimed that Mallard and his fellow MPs had denied him natural justice by not allowing him to respond to alleged inaccuracies in Wevers' report.

[54][55][56] On 22 August 2019, Mallard attracted media attention in New Zealand and abroad when he fed Labour MP Tāmati Coffey's infant son Tūtānekai Smith-Coffey during a parliamentary debate.

[65] In late January 2020, Mallard was sued by a parliamentary staff member who alleged that the Speaker had defamed him by claiming in May 2019 that a rapist was working at Parliament.

A member of the Taxpayers' Union dressed in a pig's mascot costume also held a mock invoice during the proceedings before being asked to leave due to an objection by Labour MP Duncan Webb.

Prime Minister Ardern criticised Mallard's actions as "totally inappropriate" but rejected calls by the National and ACT parties to dismiss him from his position as Speaker.

[9] In early May 2022, Mallard, in his capacity as custodian of the parliamentary grounds, approved Parliament Security's issuing of 151 trespass notices against individuals who had participated in the Wellington anti-vaccine mandate protest.

[79] In response to the trespass notices against the former MPs, the National and ACT parties renewed their calls for Mallard to be removed as Speaker of the House.

Prime Minister Jacinda Ardern rejected calls to remove Mallard as Speaker and defended his decision to issue the trespass notices.

[81][82] Mallard's resignation announcement followed renewed criticism by the opposition National, Māori, and ACT parties over his decision to issue trespass notices against five former MPs.

[84] The day before, Foreign Minister Nanaia Mahuta formally announced his appointment as the second resident ambassador of New Zealand to Ireland, which he assumed in January 2023.

During speeches following Rurawhe's election, former Labour MP Gaurav Sharma used parliamentary privilege to accuse Mallard of ignoring his concerns about bullying in Parliament and refusing to provide legal support for his case.

In response, ACT Party leader David Seymour criticised Mallard's diplomatic appointment as an example of "bad behaviour" being rewarded.

[90] In the 2024 New Year Honours, Mallard was appointed a Knight Companion of the New Zealand Order of Merit, for services as a member of Parliament and as Speaker of the House of Representatives.