Anti-terrorism laws are being used (or sometimes just cited) inappropriately in a widespread fashion.
Most people remember the case of the elderly gentleman who was removed from the Labour Party conference and arrested for heckling. This was done under ant-terrorism laws. The same laws were used to remove an anti-war protestor from Parliament Square. In neither case (and these are by no means the only examples) were there any grounds to suspect that terrorism had any part to play in the activities.
There is a link with the RIPA legislation mentioned by gromit. This Act was needed, it was said, �to help combat terrorism and serious crime�. Yet we see local council officials authorising its use to catch fly-tippers, council tax defaulters, people who try to get their children into a school by claiming to live in its catchment area and people who allow their dogs to foul the pavement. These are clearly not among the �serious crimes� which Parliament had in mind when it passed the legislation.
Photographers throughout the land are threatened with prosecution under terrorism laws when they (quite legitimately) take photographs in public places.
I do not believe this particular example was a result of inappropriate or incorrect police training. I come into contact with a number of serving police officers and it is clear to me that they are encouraged to at least suggest to many miscreants that this legislation exists and may be used against them when there is not a shred of evidence to support terrorism activities. It is a convenient �catch all� to be used (often in docks, airports, railway premises and places where politicians gather) when an immediate offence (if any) cannot be identified.
And of course, once arrested (even if illegally) DNA samples can be kept and the profiles retained.