Photograph: Peter Macdiarmid/Getty Images
For some time now, a poster with an irritating yellow smiley face has adorned London buses. "Smile, you're on camera," it says, a reference to surveillance cameras on board.
CCTV is increasingly ubiquitous and has proved its worth - even on buses - with video images of the suicide bombers in the London July 7 bombings helping to shed light on the atrocity.
But when do the authorities overstep the mark on surveillance? In the eyes of a judge, the New York police department has been doing just that. He has ruled that the NYPD must stop the routine videotaping of people at public gatherings unless there is an indication that unlawful activity may occur.
The police may well protest that it is impossible to know when such illegal activity will occur so it is better to be safe than sorry. But the two specific cases cited by judge pointed to overzealousness on the part of New York's finest.
One was a march in Harlem, the other was a demonstration by homeless people in front of the home of the mayor Michael Bloomberg.
"There was no reason to suspect or anticipate that unlawful or terrorist activity might occur," Judge Haight wrote, "or that pertinent information about or evidence of such activity might be obtained by filming the earnest faces of those concerned citizens and the signs by which they hoped to convey their message to a public official."
The use of video cameras at protests is just part of the bigger debate about the "surveillance society". The issue of video surveillance in New York was raised by the New York Civil Liberties Union. In a recent report, the NYCLU warned that the proliferation of video surveillance cameras in the absence of legal or regulatory constraint, had significant implications for the rights of privacy, speech, and association.
It argued that unregulated video surveillance technology had already led to abuses, including the police's creation of visual dossiers on people engaged in lawful street demonstrations and the voyeuristic videotaping of individuals' "private and intimate conduct".
But some, presumably on the principle that there is nothing to fear if you have done nothing wrong, are unbothered by the proliferation of cameras. Katherine Mangu-Ward flips the argument on its head by stating that "more cameras and records, not fewer, may be the best guarantee against abuse of police power in the age of zero privacy".
That's not how Wim Wenders saw it. In his ironically-titled film The End of Violence, he lays out an Orwellian vision of a surveillance society. While the film may be seen as an exercise in paranoia, there is a more pertinent point about the current surveillance fad.
Cameras may help in the detection of crime but they do not necessarily prevent crime and are no substitute for actual police officers. Cameras also have drawbacks. They need monitoring and are useless without film. The danger is that the authorities come to rely too much on surveillance cameras, regarding them as a sort of security blanket beloved by some children.
