Abstract: "Lex Sportiva" has seen rapid development with the promotion of the ICAS (International Court of Arbitration for Sports). However, "Lex Sportiva" as a law is still faced with all kinds of questions. By discussing the existence of "Lex Sportiva" as a legal phenomenon, the paper analyzes the unique legal characteristics of "Lex Sportiva" and explains the rationality of "Lex Sportiva" as a legal phenomenon from the perspective of law anthropology and sociology. The paper points out that "Lex Sportiva" is an existent legal phenomenon. It further demonstrates the rationality of "Lex Sportiva" as a law from the value of law, the effectiveness of law, the social-law nature, the procedure justice of law, the stability and standardization of law and the predictability of law. The results show that "Lex Sportiva" has the nature of law, so it is a law that is existent and developing.

Key words: Lex Sportiva, law, rationality, International sports arbitration court