This paper purposes to examine the setting aside and the refusal of enforcement of arbitral awards and their implications for practitioners. The aim of challenging an award before a national court at the seat, or place, of arbitration is to have it modified in some way by the relevant court, or more usually, to have that court declare that the award is to be disregarded (i.e. "annulled" or "set aside") in whole or in part. If an award is set aside or annulled by the relevant court, it will usually be treated as invalid and accordingly unenforceable, not only by the courts of the seat of arbitration but also by national courts elsewhere. This is because, under both the 1958 New York Convention and the UNCITRAL Model Law, the competent court may refuse to grant recognition and enforcement of an award that has been "set aside" by a court of the seat of arbitration. The New York Convention set out various grounds for refusal of recognition and enforcement of an arbitration award. The provisions of the Model Law governing recognition, enforcement or setting-aside of awards are almost identical to those set out in the Convention. Especially, the New York Convention and the Model Law state that an arbitral award may be refused and set aside if a national court of the place of arbitration finds that the award is in conflict with the public policy of its own country. Each state has its own concept of what is required by its "public policy". It is possible to envisage, for example, a dispute over the division of gaming profits from a casino. In many states, the underlying transaction that led to the award would be regarded as a normal commercial transaction and the award would be regarded as valid. Indeed, it is a consistent theme to be found in the legislation and judical decision of many countries. If a workable definition of "international public policy" could be found, it would provide an effective way of preventing an award in an international arbitration from being set aside and refusal for purely domestic policy consideration.