On Thursday the D.C. Council began consideration of legislation to regulate the Metropolitan Police Department's much misunderstood closed-circuit television (CCTV) system. This legislation, which would codify many of the CCTV policies already adopted by police, also would specify privacy protections that our department supports. As the legislation moves forward, it is essential that the city's residents and visitors understand what the system does and does not do.

First, what it does not do.

The system does not provide round-the-clock video surveillance. Cameras are activated only during major events and emergencies -- most recently during antiwar demonstrations, the sniper investigation and the terrorism alert that coincided with the anniversary of the Sept. 11, 2001, attacks. At other times, the cameras are inactive.

Nor does the CCTV system "follow" people through the District, as some critics have claimed. The police department has 14 cameras mounted in downtown areas that have been identified as potential terrorism targets or that are frequently the sites of demonstrations. While the system can access feeds from other publicly operated CCTV systems -- including those of the Department of Transportation, the D.C. public schools and Metro -- these links occur only when these agencies ask the D.C. police to access their cameras.

Finally, the CCTV system does not monitor private space or otherwise invade personal privacy. The cameras are active in public spaces only -- sites where the courts have held that people can have no expectation of privacy. Further, police regulations specifically prohibit the singling out of people because of race, gender or other characteristics. The CCTV system does not use any biometric or "face recognition" technology, nor does it have the ability to monitor audio.

Now for what the system does do.

The CCTV system provides police with another tool to protect our city during major events, emergencies and alerts. The cameras are not intended to replace officers on the street. Rather, they allow the police department to deploy officers more effectively.

During heightened threats of terrorism, for example, CCTV allows police to monitor critical areas for unusual activity. The threat of terrorism in the nation's capital remains real, but the city cannot afford to station police officers at every potential target while continuing to staff neighborhood patrols.

CCTV also helps the police better manage major demonstrations and protect peaceful protest. Consider the April 2002 demonstration in support of Palestinian rights. When protesters began massing behind a makeshift fence, officers at the scene feared that the protesters might be preparing to rush police lines and began readying themselves for a possible confrontation. But the camera showed that the demonstrators were less numerous than estimated and that they were using the fence not as a weapon but as a prop, to symbolize the "captivity" of their people.

Finally, the CCTV system could be valuable in an armed, Columbine-like incident. We all hope that we never need to put the system to such a use, but should violence occur in one of our schools, CCTV could save lives by giving officers a much clearer picture of a rapidly changing situation.

Whether CCTV can be equally effective in combating neighborhood crime remains a matter for study. The Metropolitan Police Department has not pursued the idea of placing cameras in residential neighborhoods, although it has received requests from numerous residents and civic organizations. The D.C. Council's proposed legislation would authorize a small number of pilot projects to explore the technology's usefulness in neighborhoods. My department supports this careful approach to what would be a significant expansion of the CCTV program.

In the meantime, D.C. residents and visitors can be assured that the closed-circuit television system is not Big Brother but is instead a limited and prudent use of technology that is helping to safeguard our city during these dangerous and uncertain times.

-- Charles H. Ramsey

is chief of the Metropolitan Police Department.