In 1996, Garland published the second edition of the Encyclopedia of Police Science, edited by the late William G. Bailey. The work covered all the major sectors of policing in the US. Since then much research has been done on policing issues, and there have been significant changes in techniques and in the American police system. Technological advances have refined and generated methods of investigation. Political events, such as the terrorist attacks of September 11, 2001 in the United States, have created new policing needs while affecting public opinion about law enforcement. These developments appear in the third, expanded edition of the Encyclopedia of Police Science.