counterterrorism programs,1 and it provides a framework for making decisions about deploying and evaluating those and other information-based programs on the basis of their effectiveness and associated risks to personal privacy.

The most serious threat today comes from terrorist groups that are international in scope. These groups make use of the Internet to recruit, train, and plan operations, and they use public channels to communicate. Therefore, intercepting and analyzing these information streams might provide important clues regarding the nature of the terrorist threat. Important clues might also be found in commercial and government databases that record a wide range of information about individuals, organizations, and their transactions, movements, and behavior. But success in such efforts will be extremely difficult to achieve because:

  • The information sought by analysts must be filtered out of the huge quantity of data available (the needle in the haystack problem); and

  • Terrorist groups will make calculated efforts to conceal their identity and mask their behaviors, and will use various strategies such as encryption, code words, and multiple identities to obfuscate the data they are generating and exchanging.

Modern data collection and analysis techniques have had remarkable success in solving information-related problems in the commercial sector; for example, they have been successfully applied to detect consumer fraud. But such highly automated tools and techniques cannot be easily applied to the much more difficult problem of detecting and preempting a terrorist attack, and success in doing so may not be possible at all. Success, if it is indeed achievable, will require a determined research and development effort focused on this particular problem.

Detecting indications of ongoing terrorist activity in vast amounts of communications, transactions, and behavioral records will require technology-based counterterrorism tools. But even in well-managed programs such tools are likely to return significant rates of false positives, especially if the tools are highly automated. Because the data being analyzed are primarily about ordinary, law-abiding citizens and businesses, false positives can result in invasion of their privacy. Such intrusions raise valid concerns about the misuse and abuse of data, about the accuracy


In this report, the term “program” refers to the system of technical, human, and organizational resources and activities required to execute a specific function. Humans—not computers—are always fully responsible for the actions of a program.

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