One of the most tantalizing questions human intelligence has posed itself since the beginnings of time is whether we are alone in the Universe. And if not, where are “the others,” and is it possible that these “others” may contact us, with or without our knowledge? Scientific literature abounds with theories pro and con, and if any subject ever lent itself to make-believe it is this one. Connected with the scientific theories on the subject, which are so often misunderstood, popular belief has led to a steady stream of publications which have done nothing if they have not greatly hampered the real issue. In legal circles the subject of possible contacts with extraterrestrial intelligence was first discussed in the literature in the early 1960's when, among others, Andrew Haley wrote, in 1965, about “Space Law and Government.” This publication appeared in the midst of the United Nations preparations for what was to become, in 1967, the Outer Space Treaty. Though the idea of an international protocol governing actions after the detection of a signal from extraterrestrial intelligence has never been on the agenda of the United Nations Committee on the Peaceful Uses of Outer Space, space lawyers continue to think and to write about that subject. Recent advances in spaceflight, in particular the Voyager missions to the outer planets of our solar system, give the subject a new impetus. The present paper is intended to dwell upon present scientific thoughts about the likelihood that a signal from extraterrestrial intelligence will be detected in the near future. Although this likelihood appears to be remote, it seems, nevertheless, worthwhile that discussion continues in space legal circles regarding the formulation of an international protocol for activities following the detection of a signal from extraterrestrial intelligence. Since the confirmed detection of a signal from extraterrestrial intelligence could well be of crucial importance for the continuing existence of the Earth and its inhabitants, such a protocol cannot be formulated better than at present, when no such detection has been made as yet. Before a protocol can be formulated, however, a great many questions must be answered at least tentatively, e.g. the following ones: • - What are the astronomical, exobiological and philosophical probabilities that a signal from extraterrestrial intelligence will be detected and recognized as such? • - Which person(s) will, in all likelihood, be the one(s) to detect such a signal? • - What should be the criteria to identify an extraterrestrial signal as intelligent? • - To which person(s) should the establishment and application of such criteria be entrusted? • - If a signal is identified beyond doubt as intelligent, which person(s) should undertake to decipher its contents and to establish whether the signal was accidentally received on Earth, or premeditatedly sent to Earth? • - Which person(s) should determine the distance from Earth of the transmitter of the signal? • - Depending on the answers to the latter two questions: what actions should be taken, and by whom? The present paper offers some replies to these, and other related questions. Following the resume of the replies, the main conclusions of the paper regarding an outline of the proposed protocol are that: 1. 1. The scope of the protocol must be international. 2. 2. An international forum, or committee, representing the entire world population in this matter should be established. 3. 3. The competence and authority of the forum, or committee, should include the opportunity to decide that no activities following the detection of a signal from extraterrestrial intelligence shall be undertaken. 4. 4. If the forum, or committee, decides that a return signal shall be sent, the forum or committee should have the authority to decide upon the contents as well as upon the means of transmission of the return signal.