本文企圖以牛津語言分析學派法律哲學家哈特(H. L. A. Hart)的思想為鎖鑰，解開「國際法為何註定成為欠缺強制力的『弱法』」之難題。本文首先將以哈特所創的「法律雙重結構理論」，剖析近代世界之國內法與原始社會之法律（國際法的型態亦雷同於原始社會之法律）的差異。另外，本文將藉助哈特所提出的「個體之間大致上的平等」、「可被傷害性」…等等由觀察社會事實而得出的學說，闡明「國內社會與國際社會的成員之性質完全不同」，此亦註定了國內法與國際法不可能有相同的實效性。最後本文將檢驗一種當今流行的錯誤看法，即以為「歐洲聯盟」已經突破了傳統的主權形態，藉此驗證「國際法至今仍未脫離『弱法』的本質」。

Based on the theories of the legal philosopher H. L. A. Hart belonging to the Oxford analytical school this essay tries to solve the enduring problem "why the international law has been destined to be the 'weak law'"? First this essay will investigate the differences between the modern municipal law and the law of the primitive societies by means of Hart's doctrine of the "double levels of law". That is to say the modern municipal law is a combination of the "primary rules" and the "secondary rules". On the contrary, the law of the primitive societies and the international law are, first of all, merely composed of the "primary rules". Then this essay will show that the concepts like "human vulnerability" "approximate equality" can play the decisive roles to solve our problem. At the end the operation of the European Union will be examined. Thereby, it will be proved that even the EU has not changed the essential characteristics of the international law yet. In short, the international law remained the "weak law" until today.