The Antarctic Treaty marked a milestone in the treatment of Antarctica. This Treaty possesses mechanisms that have so far been effective in protecting the Antarctic territory. The article, that is the product of the research project “Cátedra Bernardo O’Higgins” in support of teaching, sets out what and how this mechanism operate, but in turn provides that the operation of mechanisms is only applicable to States party to the Antarctic Treaty. How then defend on the Antarctic territory of States not party to the Antarctic Treaty? The answer to this question arises is to say that the evolution of the “Question Antarctica” has created custom in international law, so that the principles of the Antarctic Treaty are enforceable against third State not party to that treaty.