The dismissal of a legal challenge to the investigative powers of the Legislative Council is a victory not only for lawmakers, but also for common sense. If the power to summon witnesses could be exercised only by the full Legco, rather than a select committee, its proceedings would become unwieldy and the legislature unworkable. The High Court has, therefore, provided a welcome clarification of the law. A broader, but no less important, issue was also raised by the case: how the courts should interpret our city's constitution, the Basic Law. Mr Justice Andrew Cheung Kui-nung's ruling reinforces common law principles and upholds the separation of powers between the legislature, government and courts. It is a reassuring decision. The case arose from an investigation by a Legco select committee of the post-retirement employment of former director of housing Leung Chin-man by a developer that had profited by a decision taken on his watch. It led to the constitutional challenge by Henry Cheng Kar-shun, chairman of New World China Land, to a select committee's power to compel him to be a witness. This centred on whether the courts should rely on the meaning of the language used in the Basic Law in the light of its context and purpose, or whether they should take into account old documents that purport to show what the drafters intended 20 years ago. Article 73 of the Basic Law gives Legco the power to summon witnesses to give evidence. Because it does not expressly say committees can exercise that power, Cheng's counsel argued that the law drafters did not intend them to have it. This, it was argued, was supported by documents shedding light on the drafters' intentions. Lawyers for the legislators, however, cautioned against relying on Basic Law drafting materials because they were not all publicly available. The judge relied on the wording of the law, seen in its proper context. He found the old documents to be of little help and pointed out that the Basic Law is a 'living instrument', In other words, it must be interpreted in the light of Hong Kong as it is today, rather than as it was at the time the constitution was drafted. The reality is that the power of Legco committees existed before the Basic Law was drafted and there is nothing to suggest this was intended to change as a result of the handover. It has been used many times since. Cheng's lawyers prepared an impressive case and their arguments were eloquently presented. But the judge ultimately rejected every one of them. He was right to do so. Lawmakers are elected as guardians of the public interest to monitor the government, and scrutinise its activities and its use of public resources. They do this not only through questions and debate in the council chamber, but also through the work of various committees that vet legislation, review accounts and budgets or look into matters in the public interest. The inquiry into Leung's post-retirement job, which he resigned from within days amid allegations of conflict of interest, is a good example. Without committees vested with powers to summon witnesses, the legislature would be unable to properly perform its duty. Indeed the government itself, appearing as an interested party to maintain 'the integrity of the constitution of Hong Kong', supported the lawmakers' powers in the name of good governance. Yesterday's judgment upholds Legco's independence, and affirms the common law principle that the courts do not interfere in its internal affairs. This is especially important as we look to reforms that should see the legislature more democratically elected.