Among the many general problems of international law in issue in the Namibia Case, the question of the legal consequences of illegality under public international law is certainly one of the more important ones. Strictly speaking it was the central issue; indeed, the question put to the Court by the Security Council was to determine “the legal consequences for States of the continued presence of South Africa in Namibia”, and it referred to Security Council Resolution 276 (1970), which declared that continued presence to be illegal. Now both in the Advisory Opinion itself and in the separate and dissenting opinions, taken together, rather more attention is paid to other questions of law. in particular the question of the legality or illegality of the continued presence itself, than to the question of the permissible, or even mandatory, reaction to such illegality. Of course there is – as we will see later – a link between the two sets of problems; but. in the first instance, they could be treated separately. There are indeed – again, in the first instance – good reasons for such separate treatment. From any legal point of view it could hardly be irrelevant that a given factual situation is the result of conduct contrary to legal norms, and it would seem a priori reasonable that the law should attach some legal consequence in respect of the person whose conduct is involved. Nevertheless, the law relating to sanctions (in the largest sense of the word) is derivative law and, as such, cannot be unrelated to the peculiarities of the norms, the negation of which is “illegal”. But, on the other hand, the sanction is situated in the present, it reacts to the past, and prepares the future. In view of all this, it is hardly surprising that in this field of law relating to sanctions, there is even more uncertainty than in the field of the more direct (substantive) law relating to the rights and duties of States under a “model” of a peaceful international society!

In classic international law – as was to be expected – there is a close relatioship between substantive law and law relating to sanctions.