Undercover New York City police officers have been conducting covert surveillance of political, social and religious groups since Sept 2002, after administration of Mayor Michael Bloomberg persuaded federal judge to enlarge Police Dept’s authority in wake of 9/11 terror attacks; until 9/11, secret monitoring of events where people express their opinions was among most tightly limited of police powers; videotape images reveal presence of disguised officers, some hoisting protest signs, at seven public gatherings since Aug 2004; this includes Republican National Convention, where sham arrest of man secretly working with police led to bruising confronation between officers in riot gear and bystanders; pictures of undercover officers are culled from unofficial archive of civilian and police videotapes by Eileen Clancy, forensic video analyst who is critical of tactics; Police Dept’s chief spokesman Paul J Browne says powers obtained after 9/11 have been used exclusively to ‘investigate and thwart terrorists’; refuses to describe any limits dept places on surveillance at public events; officials say no one has complained of personal damage from information collected over recent months, but participants in protests, rallies and other gatherings say police have been disruptive presence; photos (M)
Source: Police Infiltrate Protests, Videotapes Show – The New York Times