Because of the great rapidity with which an inflammable international situation can materialize and become critical, and because of the overtones of world holocaust which accompany such situations, an organization designed to keep peace in our present world must be able to act quickly and positively, and in modes that will not of themselves compound the crisis. Mr. Schachter points out that legal precepts and precedents are essential to effective on-the-spot peacekeeping action by the United Nations. For they, on the one hand, provide a framework within which the peace-keeping agency and its members may operate and, on the other hand, make possible confidence in the legality and impartiality of the agency. He proceeds to examine United Nations peace-keeping operations as occasioned both by frontier conflicts and internal turmoil, tracing the role of legal principles in the evolution of an effective peace-keeping apparatus and drawing to light the importance, over and above the principles themselves, of their impartial, consistent, and reasoned application in a manner characteristic of “law.”