Dr. Brandon S. Centerwall, professor of epidemiology at the University of Washington, conducted a landmark 1989 study which stated that "it is estimated that exposure to television is etiologically related to approximately one-half of the homicides committed in the United States, or approximately 10,000 homicides annually, and to a major proportion -- perhaps one-half -- of rapes, assaults and other forms of interpersonal violence in the United States." A representative of the American Psychological Association testified before the House Energy and Commerce Committee's Telecommunications and Finance Subcommittee and the Senate Judiciary Committee's Constitution Subcommittee that the cause-and-effect link between TV violence and human aggression has been well established for nearly 20 years. Until recently the TV networks have been reluctant to change. That is why in 1990 Congress passed the Television Violence Act, which allowed the networks to cooperate and develop programming standards. Barring legislation, congressional hearings cannot accomplish much without unified grassroots pressure from citizens. Ultimately, citizen letters, phone calls, and faxes are the best means of reducing televised brutality and thus curb crime. Also make a note of the products or services advertised during violent programs and send letters of complaint to the leaders of those companies.