In the late periods of Chosun and Imperial Korea, Japan exerted enormous efforts to secure control over Korea through lawful process. In the process of securing her control over Korea, Japan resorted not to the military power to make Korea surrender, but to the diplomatic strategy to make Korea transfer part of her sovereign power through treaties. Under such circumstance, Japan imposed modern western legal system on Korea, which undoubtedly functioned very effectively for the Japanese colonialism, but left quite negative influence upon the legal system and the legal practice of Korea. Since the annexation of Korea in August, 1910, there had been several scattered anti-Japanese movements on regional level, but, after the March First Independence Movement, anti-Japanese movements took place all over the country on a nation-wide scale. In the March First Independence Movement, more than two million people participated in more than 1,542 demonstrations, where about twenty five thousand people were either killer or injured and about five thousand people were arrested. Those figures are cited from the records of trials on the March First Independence Movement performed by the Japanese colonial courts. Those records show that Koreans were put to the trial of the Japanese colonial courts and tried by the repressive laws of the Japanese colonial authority. Furthermore, those records function as primary materials that can provide important clues to the understanding of what kind of repressive laws the Japanese colonial courts applied to the accused and how the repressive colonial laws changed. The March First Independence Movement was the manifestation of the spirit of independence and the utmost expression of the national spirit and potentiality of the Korean people. In addition, it also was an outward articulation of democratic political consciousness of the Korean people that had been grown since the opening of the country. However, as it could not achieve its original political objectives such as the restoration of sovereignty and the independence of nation, it had to be succeeded by more continuous and organized movement. After the March First Independence Movement, the Japanese colonial authority set about the arrangement of the colonial legal system to tighten its colonial rule. On the other hand, Korean patriots established provisional government abroad and executed more organized anti-Japanese activities for independence and the establishment of an independent and sovereign nation state. This paper will examine how the Japanese colonial authority operated the colonial legal system in dealing with the anti-Japanese movement with a primary focus on the security-related laws and how the colonial legal system changed after the March First Independence Movement. In addition, this paper will inquire into the legal significance of the establishment of the Korean Provisional Government and constitution as the legal basis of the provisional government from the perspectives of continued anti-Japanese independence movement. So far has been examined the operation and development of the colonial legal system after the March First Independence Movement and its influence upon the legal consciousness and practice of the Korean people till the present time. For further research in the legal issues related with the March First Independence Movement, the following three issues should be taken into proper account. Firstly, the illegality of the Japanese colonial rule in Korea should be reexamined. The establishment of government of the Republic of Korea was not an initiation of a new state, but the restoration of sovereignty of the Korean people that had been long lost since late Korean empire. During the Japanese colonial rule from 1910 to 1945 and the U.S. military administration from 1945 to 1948, it was only that the Korean people could not exercise their sovereignty. In other words, during that time, the Korean people were still the subject of the sovereign right, but they lacked the legal capacity to exercise it due to foreign oppression. As the treaty of protection in 1905 and the treaty of annexation in 1910 were signed under compulsion, they undoubtedly were null and void ab initio. Moreover, the treaties were signed by the higher governmental officials who had been detained in palace without a commission of full powers and they lacked ratification, as was well established historical facts. Secondly, as the March First Independence Movement took place all over the country, it is necessary to collect and analyze the records of trials in North Korea. It is very regretful that materials in North Korea have not been collected and examined so far. Academic exchange with North Korean scholars should be considered for further research in the March First Independence Movement. Thirdly, as mentioned above, the colonial legal system has affected the legal system and culture of Korea to a considerable degree till the present time. In fact, under the absolutism of the Meiji constitution that advocated the pseudo-theocracy of the Japanese emperor, colonial legal system already had limits in executing constitutionalism in the true sense of the word. Some argue that colonial legal system played positive role in adopting modern western legal system such as constitutionalism, civil autonomy, the principle of nulla poena sine lege (the principle of legality), etc., but such positive aspects were yet superficial, cause the repressive and compulsory nature of the colonial legal system still have negative influence upon our legal practice. It might be correct to say that the colonial legal system rather impeded the subjective and autonomous development of the modern legal system in Korea. Vied in this light, efforts should be made to break from the nondemocratic and nonautonomous elements in our legal system, as will be the liquidation of the antinational and antidemocratic vestiges of the Japanese colonialism.