In relation to principles as a source of law, Article 38 of the ICJ Statute reads:
1. The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shall apply:....
c. the general principles of law recognized by civilized nations;...
Reflecting on this, one authority has written:
"Writers disagree on the substance and content of general principles of law, as well as on their legal scope and relationship with the other main sources, namely treaties and customary law. "Some authors link these principles with the idea of natural law. Some others, basing ther views on arbitral compromises from the 19 th century, connect them with equity. Following Grotius in this respect, Charles Fenwick was of the opinion that these principles were deduced from the fundamental principles of morality and justice, together with the more specific principles from civil law codes and from Anglo-Saxon Common law of judicial precedents. "Some authors see in the inclusion of general principles in Article 38 of the statute of the Hague Court, a defeat of positivism, i.e., an indication of the impossibility of reducing the entire system of international law to the will of the States. On the contrary, some other authors consider these principles as precepts of positive law, because of their being recognized by civilized nations’ and being rules in force in municipal legal systems of States. A third group of writers tend to reduce the application of these principles to the private law analogy or to legal reasoning in general."
This extended quotation is from pages 14 and 15 of V. D. Degan’s Sources of International Law, (Nijhoff, 1997: Jx60 D363 1997, 2nd floor, temporarily on reserve for this course). I have quoted it at length to give warning of the overall mushiness of this area both in terms of the law and as a subject for research.
The Restatement, Section 102(4) reads:
(4) General principles common to the major legal systems, even if not incorporated or reflected in customary law or international agreement, may be invoked as supplementary rules of international law where appropriate.
The comments and illustrations to this section include these thoughts;
"General principles as secondary source of law: Much of international law, whether customary or constituted by agreement, reflects principles analogous to those found in the major legal systems of the world, and historically may derive from them or from a more remote common origin.... ...General principles common to systems of national law may be resorted to as an independent source of law. That source of law may be important when there has not been practice by states sufficient to give the particular principle status as customary law and the principle has not been legislated by general international agreement. "General principles are a secondary source of international law, resorted to for developing international law interstitially in special circumstances. For example, the passage of time as a defense to an international claim by a state on behalf of a national may not have had sufficient application in practice to be accepted as a rule of customary law. Nonetheless, it may be invoked as a rule of international law, at least in claims based on injury to persons, because it is a general principle common to the major legal systems of the world and is not inappropriate for international claims. Other rules that have been drawn from general principles include rules relating to the administration of justice, such as the rule that no one may be judge in his own cause; res judicata; and rules of fair procedure generally. General principles may also provide ‘rulesof reason’ of a general character, such as acquiescence and estoppel, the principle that rights must not be abused, and the obligation to repair a wrong. International practice may sometimes convert such a principle into a rule of customary law."
It is interesting to note that the troublesome reference to "civilized nations" in the ICJ statute has evolved into the gentler "common to the major legal systems" in the Restatement.
The expression of this concept is more familar to Civilians than it is to common lawyers. Most civil codes have a statement to the effect that in the absence of express law, judges can turn to general principles to resolve disputes.
Chilean Civil Code, Article 24 :
En los casos a que no pudieren aplicarse las reglas de interpretación precedentes, se interpretarán los pasajes obscuros o contradictorios del modo que más conforme parezca al espíritu general de la legislación y a la equidad natural. The Civil Code of Qubec, Preliminary Provision, Clause One:
The Civil Code of Quebec, in harmony with the Charter of human rights and freedoms and the general principles of law, governs persons, relations between persons, and property. Code Civile Suisse, Article 4:
Pouvoir d'appréciation du juge: Le juge applique les règles du droit et de l'équité, lorsque la loi réserve son pouvoir d'appréciation ou qu'elle le charge de prononcer en tenant compte soit des circonstances, soit de justes motifs.
An older book dedicated to this subject is Bin Cheng's 1953 monograph General principles of law : as applied by international courts and tribunals, (2nd Floor, JX2000 C421G28). A more recent article is Christopher A. Ford's Judicial discretion in international jurisprudence: Article 38(1)(C) and "general principles of law", in 5 Duke Journal of Comparative & International Law 35-86, (1994).