She defeated Davison by 2,804 votes, and joined thirty-three other Liberals in forming the Official Opposition to Premier William Davis's Progressive Conservative government.

Copps ran for the leadership of the Ontario Liberal Party in 1982 following Smith's resignation, and despite her lack of experience finished second against David Peterson.

Copps was personally elected, defeating New Democratic Party candidate David Christopherson by 2,661 votes, but had relatively few allies in the House of Commons for the next four years.

She became a prominent member of the "Rat Pack," a group of young Liberal MPs who made it their business to bring misery to the Mulroney government.

During the 1993 election campaign, Copps promised during a Canadian Broadcasting Corporation "town hall" program that she would resign if the GST was not abolished.

During the by-election, Reform put up billboards around her riding, one featuring a pig at a trough with "SHEILA" marked on it; and another with her picture and, "Promise to cut the GST: It worked last time!"

During her victory speech, she noted that the Liberals "kicked butt" in the by-election; a controversial editorial cartoon in the right-wing Toronto Sun tabloid the next day portrayed Hamilton East voters as "buttheads."

Following Jean Chrétien's announcement of his intent to retire in February 2004, Copps became the first candidate to officially declare for the party leadership.

Despite her efforts to build support among women, minority groups and the party's left-wing, she began and ended the leadership contest well behind the overwhelming favourite, Paul Martin.

[8] Riding redistribution placed Copps in a serious nomination battle with another Liberal MP, Tony Valeri, who was named to Martin's cabinet as Minister of Transport.

In July 2005, Hamilton police announced a formal end to the investigation after finding no evidence to substantiate Copps's allegations including tampering of her telephones on the day of the nomination.

In her first public engagement after departing politics, she accepted a role in a Kingston, Ontario dinner theatre production of Steel Magnolias.

[10] Her second autobiography, Worth Fighting For, was published by McClelland and Stewart in October 2004 and resulted in further public controversy with Paul Martin and other members of the Liberal Party.

Copps alleged that Martin had put a pledge in his 1995 budget to rescind the "outdated" Canada Health Act and further claimed that her intervention had the offending line removed from the document.

Her allegations were denied by Martin and David Dodge (who Copps claims faxed her the draft of the budget), Diane Marleau (who was Health Minister at the time), and others.

She also hosted a weekly syndicated radio talk show, Weekends with Sheila Copps, focusing on lifestyle issues such as health and financial planning.

In March 2006, the Saint-Jean-Baptiste Society of Montreal, a prominent sovereigntist group, demanded $100,000 from Copps, claiming that she had defamed them in a television interview on January 6, 2006.

Held on March 23, 2006, the event was attended by a host of prominent Liberals, including former Prime Minister John Turner and Aline Chrétien.

As the daughter of late Hamilton Mayor Victor Copps, she has long been the object of speculation as to whether or not she would follow in the footsteps of her father,[12] recently stating that, if she were to return to politics, she would do so "it would be in my hometown and nowhere else.

[21][22] After Jody Wilson-Raybould and Jane Philpott resigned from their posts citing the government's handling of the matter, Copps repeatedly publicly called for their "firing" in the form of dismissal from the Liberal caucus.

Copps argued Wilson-Raybould and Philpott's resignations amounted to a betrayal of Justin Trudeau's leadership and their presence continued to foment internal political divisions within the Liberal caucus.

When queried about the racial undertones behind her messaging and reasoning, Copps responded: "Anybody who knows me knows I'm not a racist … there is a higher test for women, for minorities, for Indigenous people.