Leading article: The snapping of trust

Public trust in the police, as a recent inquiry into their handling of the G20 protests concluded, depends on a very narrow dividing line between acceptance of the authority of police and the perception of the arbitrary exercise of their power. So long as the demonstration of authority appears directed towards a general good, the British public is largely tolerant of ill-defined power. Once the police seem to use their power in a wilful fashion, however, public consent to authority is broken .

That is the case with the use of powers under the Terrorism Act to stop people photographing buildings or scenes within areas designated as being likely targets of terrorist attack. Most people would agree that Britain is now vulnerable to attack and that the surest way to safeguard its citizenry is to keep an eagle eye on possible plots at an early stage.

On the other hand, anything that sniffs of officiousness or excessive exercise of powers grates against a very British antipathy to bullying and unfairness. Intervening to prevent photographers or ordinary citizens taking snaps of St Paul's or even a fish and chip shop in Chatham are in one sense the confirmation of the Ealing comedy aspect of British authority, idiotic in its interfering.

But they also go to the core of the whole problem of the wide-ranging and potentially open-ended powers given under recent security legislation. The situation is made worse by the fact that the citizen thus accosted is unaware that the area is designated as a likely target, nor are they made fully aware of their rights, to refuse to give his or her name and address, for example.

The police authorities would have us believe that this is just a matter of training. Spend a bit more time educating officers as to what the law says, and all will be well. The evidence suggests that it is more fundamental than this. Too rarely do police seem to understand the purpose of legislation rather than its powers. That is a question of culture. It is also an issue of the law itself. Photographers are not the only victims of a legal system growing too oppressive under the guise of preventing terror. The balance needs to be redressed in favour of the ordinary citizen going about his life in presumed innocence.