what are the sources of international law??

Whereas bilateral treaties or treaties between only a few states may best resemble a contract between individuals, multilateral treaties such as the UN Convention on the Law of the Sea are often referred to as “law-making treaties” in that they represent as close as the international legal order gets to international legislation. Widely accepted multilateral treaties, such as the Vienna Convention on the Law of Treaties itself, are often taken as firm indicators of the content of customary international law on the topic.  

To access the Treaty Series page, which contains further information on treaties and a database of treaties to which Ireland is a party, please click here.

The treaty law section of the website of the United Nations provides a useful glossary of many of the terms used when referring to treaties, for example ratification, accession, declaration, etc. To access the glossary click the following link.

To access a table of multilateral treaties deposited with the UN Secretary General, click on the following link to the table which is correct as of 12 May 2006:  Table of Treaties (PDF 298kb). Please note: treaties concluded before 26 June 1945 and terminated treaties are not included in this table.

Custom and State Practice 

In the absence of a treaty governing relations between two or more states on a particular topic, what is important is evidence of the existence of consensus among states as to what the law should be, or, in other words, state practice combined with a recognition that a certain practice is obligatory. If sufficiently widespread and consistent, such practice and consensus may constitute customary international law.

Evidence of custom may be found among the following sources: diplomatic correspondence, opinions of official legal advisers, statements by governments, United Nations General Assembly resolutions, comments by governments on drafts produced by the International Law Commission, the decisions of national and international courts. However, as with all matters of evidence, the weight which can be given to a particular statement varies greatly depending on the circumstances in which it was made.

To access statements made by Ireland on certain international legal issues, please click here. Article 38 of the Statute of the International Court of Justice includes among the possible sources of international law, “judicial decisions” as a subsidiary means for the determination of rules of law.

For access to the website of the International Court of Justice, click on this link

Apart from decisions of international judicial bodies, decisions of a national court may amount to a statement of what that court considers to be international law on a particular matter. Such a decision would only carry weight as evidence of international law where the court is of very high standing and where the international law issue is central to the case and receives careful consideration. So, for example, important decisions of the United States Supreme Court (such as 1900 case, The Paquete Habana), the House of Lords (such as the Pinochet Case) and the Irish Supreme Court (such as The Government of Canada v The Employment Appeals Tribunal) have influenced the development or interpretation of international law.  

In addition, decisions of national courts may in themselves be evidence of state practice on a particular topic. In an important early case, The Lotus (1927) the Permanent Court of International Justice examined decisions of French national courts in order to discover what the state practice of France was on the subject at hand.