The panel last night on subway security was billed as “an experiment in participatory democracy,” one that demonstrated that democracy can be messy.

The two-hour session at the CUNY Graduate Center in Midtown, taped by WNYC to be aired on “The Brian Lehrer Show” today and Thursday, began with an informal opinion poll of audience sentiment on such hot-button issues as the subway bag searches and the surveillance cameras that the Metropolitan Transportation Authority plans to install throughout the transit system.

“All you have to do is listen with an open mind rather than just looking for the person who agrees with you and cheering them on,” the host of the panel, Brian Lehrer, advised his audience.

Such a dispassionate audience reaction was not to be. Within minutes, the two-hour session was abruptly hijacked by four audience members who shouted their disapproval of the Police Department’s policy of searching bags in the subways and their abhorrence of anyone – such as a panelist from the Manhattan Institute, Heather MacDonald – who said the police should be able to use race as one measure in deciding to stop and search subway riders rather than randomly conducting their searches. Security officers removed the rowdy audience members.

“To look for terrorists randomly is a deliberately stupid policy,” Ms. MacDonald said of the police policy. She added later that stopping people on the basis of “suspicious behavior,” as other panelists argued, forces police to categorize people based on wide generalizations not unlike racial profiling.

Neither her argument nor that of a professor at New York University, Stephen Ellmann, who said such searches would be warranted if a threat was imminent, changed the opinions in the audience, two-thirds of whose members indicated earlier that they objected to the policy of searching bags in the subway.

It was with a sigh that Mr. Lehrer observed that “very few people have changed” their beliefs.

The second panel, which focused on the use of surveillance cameras in the subway, faced a conflicted audience, which recognized that cameras were fundamental in identifying the four bombers shortly after the July 7 subway attacks in London, even if the monitoring did not prevent the attack.

That ambivalence did not dissipate when the executive director of the New York Civil Liberties Union, Donna Lieberman, said surveillance cameras had become so commonplace in Manhattan that more than 7,000 cameras had been identified by the group after it canvassed less than 20% of the borough.