People in Hong Kong reap the benefits of competition in telecommunications in terms of the choice and prices of mobile phone services they are offered compared with other places. To get started, all you need is your ID card - with one exception. Anyone can walk into a convenience store and walk out with a prepaid SIM card for as little as HK$100, no questions asked, without producing identification. It can then be used to make calls anonymously and in total privacy if calling someone else with a prepaid card. Given the penetration of the ID card into our daily lives and the amount of personal data collected these days, that sounds like an exception worth keeping. Our constitutional right to privacy has, after all, proved open to abuse by people who collect personal data. Senior police officers do not think so. To them it is a loophole exploited by criminals that should be closed. Tony Liu Kit-ming, chairman of the 1,800-strong Hong Kong Police Inspectors' Association, says they use the untraceable cards for incriminating communications in a range of crimes from simple deception to highly organised drug smuggling. He wants it to be made illegal to buy a prepaid card without registering some form of identification, in line with laws in many other places, including the mainland, Singapore and Australia. Put that way the idea sounds reasonable. The government says it will monitor the situation, but that as well as privacy concerns new laws might create 'undesirable hurdles' for the prepaid card trade. There is a need to find a way of ensuring crime can be combated without unduly restricting our privacy. Curiously, as things stand, the police cannot take advantage of a covert surveillance law passed by this government to eavesdrop on criminals' conversations if they are using mobile phones with prepaid SIM cards. We suppose this is unlikely to change until it can be shown that a violent crime arousing public outrage could have been prevented if police could have traced a mobile used by the offender.