Marty is best known to Minnesota residents as an advocate on environmental issues, health-care reform, and government ethics and campaign-finance reform. He is the author of the Minnesota Health Plan, a comprehensive single payer healthcare plan. In 2016, he authored a book, Healing Healthcare, that makes the case for a universal healthcare system. Marty does not accept soft money contributions or contributions from lobbyists, and he sharply limits the contributions he will accept from any one person. Among Marty's ethics legislation was the Minnesota law banning lobbyists from giving gifts to public officials. Marty opposes the public funding of stadiums and professional sports teams and was outspoken in his criticism of proposals for new stadiums for the Minnesota Twins and Minnesota Vikings. He also is a supporter of medical marijuana, and even made an appearance in the movie "Super High Me".