Stamper is known for his role as Chief of the Seattle Police Department responsible for Seattle's response to the protests of the WTO Ministerial Conference of 1999, which eventually led to his resignation. Stamper has expressed regret about his decisions at the time. When discussing the use of chemical agents such as tear gas Norm Stamper declared it was a mistake and said "The chief in me should have said, 'For the greater good, we ought not to have brought those chemical agents out. We ought not to have, I think, raised the stakes.'"
Since his resignation, Stamper has called for the legalization of all drugs and the case-by-case release of persons incarcerated for nonviolent drug offenses. He serves as an advisory board member for LEAP as well as NORML. He has also starred in the marijuana documentary The Union: The Business Behind Getting High.
Stamper is the author of a book entitled Breaking Rank: A Top Cop's Exposé of the Dark Side of American Policing.