A requirement for the existence of customary international law , together with opinio juris , is state practice or the actual actions or omissions of states . Article 38, paragraph 1, subparagraph b, of the Statute of the International Court of Justice states that the practice relevant to establishing customary international law is that which is general and accepted as law. The last part of this paragraph refers to the element of opinio juris , but it is the word “general” that is of importance. It indicates that general, or widespread, practice— not isolated practice— is important. Determining what constitutes state practice usually requires examining historical records that indicate how states act. The more reliable the record the better evidence it is of state practice.
- Doebbler, Curtis F. J.
The Persistent Objector Rule in International Law by 
Sources of State Practice in International Law by 
Customary International Humanitarian Law - Practice by 
Customary International Law on the Use of Force by 
Customary International Law by 
The Persistent Objector Rule in International Law by 
Developments in Customary International Law by 
United States Practice in International Law by 
Surveys of state practice organized by treaty and international activities. (Legislation, case law and diplomatic practice).
A few examples are provided below.
A few examples are provided below.
