As President of the New Zealand Council of Trade Unions until 1999 Douglas led the union movement in New Zealand for over fifteen years. His union career started in the Driver's Union. He was also leader of the Socialist Unity Party in the 1970s and 1980s and stood for Parliament on occasion never gaining more than 100 votes in the Porirua electorate.
Since his retirement from the CTU Douglas has been active in local politics as a Porirua City Councillor (1998-), Porirua Licensing Trustee (2001-) and elected member of the Capital and Coast District Health Board (2004-).
An acknowledged Marxist, Douglas has moved to the right over the last two decades and sits on Air New Zealand and New Zealand Post Boards. He is also chairperson of Positively Wellington Business and a board member of the Asia NZ Foundation.
Douglas has come under increasing criticism from the New Zealand trade union movement for refusing to use his position on Air New Zealand's Board of Directors to stop the airline from cutting the pay and conditions of its workers under threat of outsourcing.
In 2006 a two hour documentary was shown on New Zealand's TV ONE about Douglas's life.