Laws enacted for the purpose of national security are essentially preventive detention laws that are meant to prevent an individual from engaging in any activity that might be prejudicial to the national interest. These preventive detention laws are different from punitive detention laws. Preventive detention laws such as the National Security Act, 1980 do not prescribe to the strict adherence of the procedural rights and safeguards that are otherwise accorded to the individuals who may be the subject of punitive detention. Thus, preventive detention laws are considered to be draconian in the sense of their perceived unwarranted intrusions upon the personal liberty of individuals that are not based upon proved facts but mere suspicion of the detaining authority as regards to the possibility of an individual engaging in Acts that are prohibited under the concerned law of preventive detention. Notwithstanding the fact that the preventive detention laws deprive the personal liberty of individuals to an extent greater than that which may be provided for under the normal statute, yet, in light of the fact that India is continuously subjected to a lot of adverse activities that have the effect of seriously impeding the normal functioning of the State, it can be considered that preventive detention laws are a necessary evil. Since, preventive detention laws directly affect the personal liberty of individuals and are a subject matter of great criticism, it becomes pertinent to have a look at the various preventive detention laws in the country as well as the opinion of the Courts with regard to the validity and limits of such laws which is the subject matter of this research and how the preventive detention laws can be harmonised with personal liberty all of which is essentially the subject matter of this research.