Someone from a foreign legal system visits a common law courthouse. In one court, a hostile judge asks a lawyer: "Is there any legal precedent that I CAN do this?" In the court next door, a hostile judge asks another lawyer: "Is there any legal precedent that I CANNOT do this?" The poor visitor is left to wonder: What is it about the common law? Do judges require case authority to tell them what they can do? Or do they require case authority to tell them what they cannot do? The key to understanding this query is to realise that legal problems present themselves in different forms. There are cases in which the facts are clear and the wording of the law is unambiguous, where the judge may have little alternative but to apply the law irrespective of his personal perception of "moral merits". But in many cases the matter is less clear cut. The application of the law to the facts may involve something subjective, such as whether someone has acted "reasonably". Or the language of the law or of a written contract may be ambiguous. Or there may be no legal precedent on the point. In these cases, the judge's perception of fairness and justice is potentially engaged. In one of my favourite articles Law as Taught and Law as Practised by the eminent British judge and jurist Sir Robert Megarry, the writer observed: "In the practice of the law there is a tendency to look at what is the fair and just and proper result, and then see whether that conclusion can be reached in accordance with the law. Of course, if there is something in your path that stops you doing this, then it stops you." The different scenes outlined at the beginning of this article are situations where the judge is trying to ascertain if there is anything which stops him doing what he wishes to achieve, as a matter of justice and fairness. When a party pursues a valid claim in an oppressive way, judges are not powerless. In a section in his article under the sub-title 'The Moral Force of the Judge', Sir Robert referred to the example of a litigant who pursued a legally valid claim in a harsh and dishonorable way. The judge made it clear that despite the legal merits, he disapproved of the litigant's conduct. The litigant was a lawyer by profession and, fearing that the judge may say unkind things about him in his judgment and thereby affect his professional reputation, he settled the case in a fair manner. Now it may legitimately be said that if a person has a valid claim, it is none of a judge's business to ostracise him for pursuing it. However, one cannot exclude the possibility that there may be very rare cases where - because of the personality or the subject matter concerned - the "moral force of the judge" can operate as a legitimate check against a harsh or oppressive use of the law. That great invention of the common law, the jury, can also assert its moral authority in such cases through the verdict or award it delivers. This topic, however, is for another day. Paul Shieh Wing-tai SC is the chairman of the Hong Kong Bar Association.