It was the underworld that coined the slogan: 'If you can't do the time, don't do the crime'. But that's not how the courts look at it in Hong Kong. Ever since a Court of Appeal judge decided foreign prisoners suffered more than home-grown felons when they were locked away for their crimes, judges have been pruning sentences to make life easier for them. It may not be much. The jail terms handed down to four Colombian robbers yesterday who attempted to snatch a briefcase from a diamond merchant were three months short of what a local could expect to receive for the same offence. Two received sentences of eight years and nine months, and two were given five years and nine months. The appeal ruling came when a Swiss-German man jailed for fraud had three months knocked off his sentence last week. The judge said life behind bars left foreigners isolated linguistically and culturally, unable to enjoy familiar food and deprived of visits from family and friends. The following day, another judge reduced a Malaysian drug trafficker's 16-year sentence by six months, partly for his 'foreignness' and partly because of his previous good character. But prisons in Hong Kong, like its judicial system, are founded on humanitarian lines. Certainly it is tough inside. It is meant to be. And it will be tougher on foreigners for the reasons the appeal judge outlined. But that comes as a natural consequence of abusing the hospitality of the SAR by committing criminal acts here. It could be considered an extra self-imposed hardship, rather than an excuse for more lenient sentencing. The judge in yesterday's case referred to Hong Kong's record as a safe place to do business. That is something worth protecting. It is among the incentives which make the city an attractive place to set up a regional office. Foreigners who commit offences here risk damaging that reputation by increasing the crime statistics. Compared with those of other Asian nations, the SAR's prison system is liberal and humane. As to be expected in a multicultural society, prison kitchens are used to coping with various dietary regimes. Prisoners can ease isolation by learning Cantonese. When British Inspector of Prisons Sir Steven Tumim toured Hong Kong's jails in 1997, he found them cleaner, brighter and better run than many in the UK. They may not be a home away from home. But do we really want word to spread abroad that foreign criminals will spend less time in them?