Since 1957, Gomery worked at the law firm Fasken, Martineau and Dumoulin in the areas of family law, commercial litigation and bankruptcy and became a partner there in 1966. In 1972, he was appointed Queen's Counsel (QC). In 1982, he was appointed to Quebec Superior Court Montreal district and from 1999 to 2005 served as President of the Copyright Board of Canada (renewed in 2002).
Gomery has also been involved in the Canadian Bar Association and Chambre des notaires du Québec. He was also President of the Comité Général des Juges de la Cour supérieure du Québec, President of the Family Law Committee from 1983 to 1993, and has been a member of the Rules of Practice Committee since the beginning.
Gomrey retired from the court bench on August 9, 2007, after turning 75, the age of mandatory retirement.
Gomery was appointed on February 19, 2004 as Commissioner of Inquiry into the Sponsorship Program and Advertising Activities (informally, the Gomery Commission) to investigate the Sponsorship scandal. Gomery's mandate is set by Section IV, clause I of the Inquiries Act which states: "The Commissioner [is] directed to perform his or her duties without expressing any conclusion or recommendation regarding the civil or criminal liability of any person or organization and to ensure that the conduct of the inquiry does not jeopardize any ongoing criminal investigation or criminal proceedings." In other words, Gomery's mandate was only to determine whether there were problems with the federal sponsorship program in Quebec between 1995 and 2003; he was explicitly forbidden to name any individuals or organizations that may have been responsible for the alleged fraud that occurred during the sponsorship program. Gomery's report, available in several parts e.g. Restoring Accountability: Recommendations, assisted the Royal Canadian Mounted Police with further investigations, which led to criminal charges being filed and prosecuted against certain key figures in the scandal.
He has been criticized by many, in particular Chrétien supporters, who saw his dealings in the commission as biased. Others also criticized Gomery's terms of reference which did not allow the inquiry to investigate Paul Martin's contracting habits as finance minister.
Jean Chrétien went to federal court to clear his name and have the Gomery report invalidated. On June 26, 2008, federal judge Max Teitelbaum criticized Gomery for making comments that indicated he judged issues before all evidence was heard and exhibited bias against Chrétien. The federal judge also ruled that Gomery's comments on "small town cheap" amounted to a personal insult against Chrétien. The court quashed the Gomery inquiry's conclusions that Chrétien and Jean Pelletier bore responsibility for the sponsorship scandal.
- "THE GOMERY COMMISSION REPORT, PHASE 2 - AN OVERVIEW"
- "Gomery pick to 'shut up' critics". Archived from the original on November 4, 2005. Retrieved June 28, 2008.
- MacCharles, Tonda. "Gomery was biased in report, judge rules", The Toronto Star, 27 June 2008.
- Clark, Campbell and Curry, Bill. "Absolving Chrétien, judge blasts Gomery", The Globe and Mail, 27 June 2008.
- Garvey, Bruce (2005-05-05). "Don't Wait for Gomery". National Post. p. A26.