Data mining has been used by the U.S. government. Programs include the Total Information Awareness (TIA) program, Secure Flight (formerly known as Computer-Assisted Passenger Prescreening System (CAPPS II)), Analysis, Dissemination, Visualization, Insight, Semantic Enhancement (ADVISE),[38] and the Multi-state Anti-Terrorism Information Exchange (MATRIX).[39] These programs have been discontinued due to controversy over whether they violate the 4th Amendment to the United States Constitution, although many programs that were formed under them continue to be funded by different organizations or under different names.[40]
In the context of combating terrorism, two particularly plausible methods of data mining are "pattern mining" and "subject-based data mining".