Sit back and relax. That is what air passengers are told soon after they settle in on board an aircraft. But too often they wake up from a nap or return from the restroom to find their belongings stolen. Even if the "cabin rats" - a Chinese term for in-flight thieves - are caught red-handed, justice may not be done. This is because our laws against theft do not go beyond the city's jurisdiction. For a long time, criminals have been taking advantage of the loophole while watching as our police officers' hands are tied. The number of reported thefts on board jumped from 21 in 2011 to 64 in the first three quarters of this year. Countries like Singapore also saw a rising trend.

It is good that local law enforcement has adopted a new approach. Instead of theft, the Department of Justice recently suggested thieves be charged with disorderly conduct - a violation covered under in-flight misbehaviour in aviation security law. This seems to be a sensible way to tackle the situation. Although the maximum penalty is two years' jail, just one-fifth of that under the Theft Ordinance, it is nonetheless an effective tool to bring criminals to justice. Since the switch in June, police have prosecuted 14 cases, in which five mainlanders have been convicted and jailed for three to four months. Hopefully, it will send the right message that Hong Kong is determined to plug any legal loophole and keep criminals away.

The problem of countries being unable to press charges against in-flight theft due to extra-territorial jurisdiction is probably not unique to Hong Kong. It remains to be seen if others can improve upon our new approach. After all, charging a thief for disorderly conduct does not reflect the true nature of the offence. The loophole is not yet plugged unless the aviation industry steps up efforts to resolve the problem. International cooperation is needed. Passengers also have to stay alert. The confined cabin environment often gives a false sense of security. Until we have the proper legislative tools in place, vigilance is the best way to deter crime.