From a statement of Caroline Frederickson, Director of the ACLU’s DC Legislative Office, given to the Senate Committee on the Judiciary, April 21, 2009:

Improving information sharing sounds like a fine goal in the abstract, but increasing the government’s authority to collect and disseminate personally identifiable information about Americans in the absence of reasonable suspicion and a specified law enforcement purpose poses significant risks to our privacy and civil liberties. In our view, any effort to expand information sharing among law enforcement agencies must be accompanied by independent oversight mechanisms and a rigorous set of standards to ensure the use of proper methods, to preserve the privacy of innocent individuals, and to maintain the accuracy and usefulness of the shared information.

The police power to investigate, when combined with the secrecy necessary to protect legitimate law enforcement operations, provides ample opportunity for error and abuse. The potential for abuse expands as the amount of information collected and the number of entities it is shared with increases. By its very nature, criminal intelligence information is often criminal intelligence information is often uncorroborated, inadequately vetted and fragmentary. At its worst, it is unreliable, misleading or just plain wrong. Just one thing is certain about ‘intelligence:’ it is only valuable to our security when it is true. If the information collected and shared among law enforcement agencies is inaccurate or irrelevant to a legitimate law enforcement function, sharing it will not improve security, and very well may damage it. Our concerns about information sharing lie in the details. We want to know what information is being collected, who is collecting it, what is done with the information once it has been collected, what authorities regulate these activities, and who is ultimately responsible for ensuring compliance with applicable federal, state, and local laws?

Protecting National Security and Civil Liberties: Strategies for Terrorism Information Sharing