Changing the rules*

Who is monitoring your frocks - and why? How far can you go in a "passive smoking situation"? Let th

Recently after a hard day’s shopping, I had a deeply embarrassing retail moment.

I set off a store alarm, and it took for ever before the staff were able to clear my name. It turned out that the culprit was a dress I’d bought hours earlier. Why did it bleep? And don’t I have the right to know when my frocks are being monitored?

Rupa Mitra, Cambridge

It sounds as though you fell victim to a passive radio frequency identification tag - a tiny microchip, detectable at distances of several metres, that is often sewn into clothing to prevent shoplifting. Usually RFID tags are disabled at the point of sale, but there is no law obliging retailers to do this - and if they remain active, they can be freely read by any receiver set to the appropriate frequency.

In fact, the tags are so under-regulated that they have become a popular method of surveillance. London Transport uses them to collect information about the movements of millions of Oyster Card holders, and as of March 2006, it had volunteered data to the police about the bus and Tube journeys of specific individuals on at least 409 occasions. An ingenious combination of RFID tags and hidden cameras allowed the Cambridge branch of Tesco's in 2003 to take secret photographs of customers picking goods off the shelves, which were then matched against faces at the cash till.

In the United States, the tags contained in food store loyalty cards have even helped wage war on terror. According to a 2002 report in New York's Village Voice, Federal agents examined the grocery purchase records of the September 11 hijackers "to create a profile of ethnic tastes and terrorist supermarket shopping preferences".

Tags in clothing arguably give the innocent no cause for alarm, except literally. But if you remain unconvinced, a few basic steps should ease your fears.

Snip the labels off all your high-value outfits. Give your entire wardrobe a precautionary boil wash. The most reliable counter-surveillance technique would be to subject every suspect item to a spin in the microwave. Be warned, however, that this can destroy the oven along with the tags.

I was interested to read your recent remarks about the smoking ban, even if you sounded a little flippant. Not everyone likes smelling like an ashtray, you know! Anyway, can you tell me what rights ordinary people will have if smokers ignore the new law? It's bound to happen.

Mark Miller, London

I apologise if I appeared anti-sanitary in any way. That was not my intention. Your question is an interesting one. A patron's initial remedy in most cases will be to demand action from members of staff - failing which, employees can be reported to the police and, with luck, prosecuted. The government is also going to set up an 0800 hotline to facilitate denunciations. As such, if ever you are faced with an emergency passive smoking situation, it should be a relatively straightforward matter to eliminate both the problem and its cause.

More generally, members of the public are always entitled to use "such force as is reasonable in the circumstances" to prevent crime. It is at least arguable, therefore, that you can use coercion to extinguish the cigarette of any stubborn smoker whom you encounter.

The degree of violence permissible would, of course, vary from place to place. A situation that merited no more than an armlock at the Ivy, say, might conceivably justify a swift knockout blow in less salubrious establishments. I strongly advise against testing either proposition, but please rest assured that you will have the law's theoretical support, and that your hygienic issues are soon to be resolved.

Sadakat Kadri is a barrister and author of "The Trial: a history from Socrates to O J Simpson" (Harper Perennial, 2006). Send your civil liberties and human-rights dilemmas to: Changing the Rules, New Statesman, 52 Grosvenor Gardens, London SW1W 0AU. This column appears fortnightly

*"The rules of the game have changed" Tony Blair, August 2005