Claude R. Thomson

After leaving Fasken Martineau late in his career, Thomson joined ADR Chambers in Toronto, which provides mediation, arbitration and other dispute resolution services. In 2014, it was announced that ADR Chambers was now the largest arbitration company in the world.

From 1993 to 1994, Thomson was the president of the International Bar Association. He was the second Canadian to serve in that post, the first being Neil McKelvey, who was also a former president of the CBA.

In 1985, Thomson was given the World Lawyer Award from the World Peace Through Law Centre (now the World Jurist Association). He was the first Canadian to receive the award. On accepting the award, he called on lawyers to oppose nuclear arms, saying: "Such weapons are illegal because they have the potential to destroy us all."

Thomson served as the president of the Canadian Bar Association from 1984 to 1985. The Canadian Charter of Rights and Freedoms had been enacted two years previously, and he announced that one of his goals as president was to work for the repeal of section 33 of the Charter, which authorizes the federal and provincial governments to override certain Charter rights for a limited period. He was unsuccessful in this lobbying effort.

In 1980–81, a number of children died at The Hospital for Sick Children in Toronto. Concerns were raised that they were being poisoned, leading to a provincial inquiry into the deaths. Thomson acted for one of the nurses who came under suspicion, vigorously defending her and chastising the commissioner, Justice Samuel Grange, for putting her under trial in the court of public opinion. He also engaged in public relations on behalf of his client, appearing on a CBC radio programme, Cross-Country Checkup, to explain his client's position. His client was not charged in the matter.

In 1980, the Southam newspaper chain closed its paper in Winnipeg, the same day as the Thomson newspaper chain closed its newspaper in Ottawa. The closures gave Thomson newspapers a monopoly in Winnipeg and Southam newspapers a monopoly in Ottawa. Eventually, the two newspapers were prosecuted under the federal Combines Investigation Act offences governing mergers and monopolistic conduct. Claude Thomson was retained to carry on the prosecution on behalf of the Crown. After a lengthy trial, the two newspaper chains were acquitted. Thomson later commented about the case: "I presented every piece of evidence I could. I asked every tough question I could think of. The judge believed the defence. That's what our system of justice is about and I have no complaints."

In the 1970s, information came to light about illegal activities by the RCMP Security Service. The federal government appointed a royal commission of inquiry, chaired by Justice McDonald, to investigate the allegations and to make recommendations. Thomson was retained by the RCMP to represent them at the commission hearings.

In 1963, an American engineer was charged with murder at an American missile base on the British overseas territory of Ascension Island in the south Atlantic. Thomson was asked to defend him. The trial occurred on the island of Saint Helena, eight hundred miles to the south of Ascension Island. The chief justice of Uganda presided over the trial. Thomson's client was acquitted of murder but convicted of manslaughter. He was sentenced to twelve years' imprisonment, which he served in England.

He and his wife, Rosemary, were married in 1958 and had five children Marguerite, Brendan, Christopher, Kelley and Campbell.

After articling with a noted litigation lawyer in Toronto, Malcolm Robb, Thomson was called to the Bar of Ontario in 1958 and to the bar of Saint Helena in 1963. Thomson spent most of his legal career as a general litigator and partner with the law firm Fasken Martineau in Toronto, developing a reputation as an intense courtroom lawyer with formidable tactical skills, and acted for parties in a large number of high-profile cases. Later in his career, he developed a practice in mediation and arbitration. He eventually left Fasken Martineau to join ADR Chambers International in Toronto, an international arbitration group. He became a Chartered Arbitrator and acted as an international arbitrator and mediator.

Claude R. Thomson QC (September 30, 1933 – November 24, 2010) was a Canadian lawyer in Toronto, Ontario. He was a well-known courtroom lawyer, and also a pioneer of alternative dispute resolution in Canada, including mediation and arbitration. He served as the president of the Canadian Bar Association and the International Bar Association.

Thomson was born in Toronto, Ontario in 1933, the son of William Thomson, a civil engineer with the provincial department of highways, and Cecile Morency. His mother was francophone but would not speak in French to her son in public, fearing it would hold him back.