LeRoy Bennett and James K. Oliver (2002: 2) identified common and constitutive characteristics of International Organizations as:

• A permanent organization to carry on a continuing set of functions;
• Voluntary membership of eligible parties;
• A basic instrument (a founding document or charter) stating goals, structure and methods of operation;
• A broadly representative consultative conference organ;
• A permanent secretariat to carry on continuous administrative, research and information functions.