In Hayek’s political theory, liberty is inseparable from the rule. In contrast to the external coercions, Hayek defines liberty as “the independence of the arbitrary will of another.” He opposes the external coercions, which are derived from the arbitrary will of another. The law, on the contrary, is the safeguard, not the counterforce, of liberty. So, he refers to liberty as “liberty under the law” or “liberty under the rule of law.” According to Hayek’s viewpoint, “law” must possess three essential characteristics: (1) generality and abstractness; (2) be known and certainty; (3) equality. The three essential characteristics constitute the “meta-legal rules” or “meta-legal doctrines” of law. If the law corresponds with meta-legal doctrines, it is “the law of the rule of law” or “the law of liberty.” Apparently, we can find that the concept of “law of nature” in modern legal philosophy has important influence on Hayek’s concept of law. He considers that the law is “found,” and not “invented”. From this viewpoint, he links the argument of “liberty and the rule of law” with his theoretical presupposition of “spontaneous order.” The obedience of the general or impersonal law, which correspond with “meta-legal rules” is in harmony with the realization of liberty. In order to explain his arguments, Hayek quotes Locke’s statement, “Where there is no law, thee is no freedom,” and Kant’s proposition that “Man is free if he needs to obey no person but solely the laws.” According to Kant’s viewpoint, the “universalizability” of law is established on the correspondence between external rules of behaviors and inner “categorical imperative” of mind. Law, with the characteristics of “universal law,” according to the principle of “intersubjectivity” is in harmony and correspondence with the realization of liberty. From Kant’s proposition, Hayek accomplishes his fundamental arguments about liberty and the rule of law.