Each year, state lawmakers across the U.S. introduce thousands of bills dreamed up and written by corporations, industry groups and think tanks. Disguised as the work of lawmakers, these so-called model" bills get copied in one state Capitol after another, quietly advancing the agenda of the people who write them. A two-year investigation by USA TODAY, The Arizona Republic and the Center for Public Integrity reveals for the first time the extent to which special interests have infiltrated state legislatures using model legislation. USA TODAY and the Republic found at least 10,000 bills almost entirely copied from model legislation were introduced nationwide in the past eight years, and more than 2,100 of those bills were signed into law. In a separate analysis, the Center for Public Integrity identified tens of thousands of bills with identical phrases, then traced the origins of that language. Model bills passed into law have ... limited access to abortion and restricted the rights of protesters. In all, these copycat bills amount to the nation's largest, unreported special-interest campaign, driving agendas in every statehouse and touching nearly every area of public policy. USA TODAY found more than 4,000 bills benefiting industry were introduced nationwide during the eight years it reviewed. More than 80 of those bills limit the public's ability to sue corporations, including limiting class-action lawsuits, a plaintiff's ability to offer expert testimony, and cap punitive damages for corporate wrongdoing.