The adoption of the Rome Statute is a significant moment for international criminal law. Before its formulation, the criminal law was governed by the sources mentioned in their statute or Article 38 of the Statute of the International Court of Justice [ICJ Statute]. Custom is one of the important sources within the ICJ Statute. The ad hoc tribunals applied custom and even formulated certain customs. The formulation of custom is considered as against the principle of legality. To avoid such criticism, the State Parties inserted Article 21 in the Rome Statute. The provision clarifies the law which the court can apply. The parties chose not to include custom explicitly. However, the wordings of the provision indicate that the custom is still a source for the court. Apart from the wording of Article 21, other provisions of the Statute give ample scope for the application of custom.

中文翻译：

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习惯作为《罗马规约》第 21 条的来源

《罗马规约》的通过是国际刑法的重要时刻。在制定之前，刑法受其规约或《国际法院规约》[ICJ 规约]第 38 条中提及的来源管辖。习惯是《国际法院规约》中的重要来源之一。特设法庭适用习惯，甚至制定某些习惯。习惯的制定被认为违反了合法性原则。为避免此类批评，缔约国在《罗马规约》中加入了第 21 条。该条款明确了法院可以适用的法律。双方选择不明确包括习惯。但是，该条款的措辞表明，该习俗仍然是法院的来源。除了第 21 条的措辞外，