Tough penalties and random tests have sent motorists a loud-and-clear message that drink-driving will not be tolerated. Horrendous accidents forced the change. Similar rethinking of the rules and laws are needed following a spate of arrests of drivers suspected of being under the influence of drugs. The government should respond as a matter of urgency; we must not wait for a tragedy to happen before acting. Transport officials have already formed a working group. The transport minister, Eva Cheng, answered questions raised by legislators in May. She said then, and her bureau this week repeated it, that the issue is complex. This is true. But no matter how complicated it may be, ways have to be quickly found to keep drugged drivers off our roads. It is, therefore, good to hear that tougher legislation is being considered. Statistics here and studies elsewhere show why. Government figures indicate one in seven people killed in road accidents over the past five years had traces of drugs in their bodies. There is no certainty that the crashes were caused by drugs, but the suspicion is enough to cause concern. Extensive surveys in Australia, Europe and North America reveal even more worrying figures and trends. They point towards an alarming prevalence of drug-driving, particularly among the under 30s. We know that there is a thriving drug culture among our city's young people; we would be foolish to believe that Hong Kong drug-takers do not sometimes get behind the wheel while high. The effect of alcohol on drivers is well known. Drugs in this regard are less studied, but we know that they equally impair the ability of users to think and respond normally. Depending on the type and quantity taken, they can cause drowsiness, loss of co-ordination, increased reaction time, vision problems, an inability to manage the unexpected, and aggressiveness. A quarter of deaths on Hong Kong roads involve alcohol. Drugs have not been as prominent, but police tell us there is a rising trend of use in our community. Authorities were sufficiently worried to start a random testing programme in Tai Po secondary schools. Random testing of drivers for alcohol began last year; serious consideration should be given to extending the practice to drugs. This is where the complications begin. Drug testing is not as easy as for alcohol. Limits cannot be set on acceptable levels of drug intake. In the Australian states of New South Wales and Victoria, portable saliva kits are used by police, but several days are needed before results can be confirmed. Blood tests are the most accurate, but permission has to be given under our laws before samples can be taken. Complexities are no reason for delay. Other governments have adopted a wide range of responses. Most have been tackling the problem for several years - in some instances, a decade or more. A great deal of leg work has been done. Sometimes, the government spends a long time looking into a problem without acting. Road rules are usually revised only after lives are lost in tragic circumstances. But we know that drug-driving is a problem. Work on redrafting the laws has to begin now.