Territorial politics

In 1970, Sibbeston was elected to a four-year term on the North West Territorial Council, after which he was defeated by William Lafferty in the 1975 Northwest Territories general election.

He was re-elected in the 1979 general election and would continue to be a Member of the Legislative Assembly until 1991.^[2] During his second term in the Legislative Assembly, Sibbeston was elected to serve in the Executive Council (cabinet).

In a 1981 incident, Sibbeston was thrown out of the territorial legislature for throwing a cup of coffee at Peter Fraser, the speaker of the legislature, during an intense debate.^[2]

He would serve six years in Cabinet until he was elected to serve as the fourth Premier of the Northwest Territories from 1985 until 1987.

Civil servant

After 1991, Sibbeston worked briefly for the Government of Northwest Territories, as a justice specialist and as a public administrator for Deh Cho Health & Social Services. He also served four years on the Canadian Human Rights Panel/Tribunal, as well as being a cultural and Slavey-language advisor for the television program North of 60.

Federal politics

Sibbeston was appointed to the Senate of Canada on September 2, 1999, on the advice of Liberal prime minister Jean Chrétien.^[3] In the Senate, one of his goals was to find a new name for the Northwest Territories.^[4] He also focused on issues such as the Mackenzie Valley Pipeline, infrastructure in the North, climate change mitigation, and increasing Indigenous engagement in the economy.^[3]

On January 29, 2014, Liberal Party leader Justin Trudeau announced that all Liberal Senators, including Sibbeston, were removed from the Liberal caucus, and would continue sitting as Independents.^[5] According to Senate Opposition leader James Cowan, the Senators will still refer to themselves as Liberals even if they are no longer members of the parliamentary Liberal caucus.^[6] Sibbeston agreed with Trudeau's decision, saying that the Northwest Territories also did not have a party system.^[2] That same month, Sibbeston defended his absence from 51 out of 70 votes in the previous parliamentary session, his reason being the nastiness of partisan party politics in Ottawa, which he was not used to in the north.^[2]

On May 5, 2016, Sibbeston left the Senate Liberal caucus to sit as an independent senator.^[7]

In September 2017, Sibbeston announced that he would resign on November 21, his 74th birthday. Sibbeston said that he would focus on his family, travel, and spirituality as well as translating Catholic liturgy into the Dene language.^[3]