In Constitutional Law, there is provided the principle of warrant request which consist of provisions that request the warrant issued by judge for several situations. According to this principle, the processes by which the warrant can be gained are stipulated in laws for each area.
To get the correct answer to the question, when and for which action the warrant should be gained, it may be important to consider comparative method with the laws of other countries and to study the general theory, but it should be preferential to look at in detail how the wording and phrasing are made in the provisions of korean constitutional law.
Case 1 and Case 2 have logical structure based on the dichotomy between the criminal investigation in which the warrant be requested and the administrative survey in which not. But the Constitutional Law provide for the arrest, detention, search and seizure, the request of law in the provision 12. 1., the request of warrant in criminal investigation in the provision 12. 3. and the request of warrant for the search and seizure in a person’s house in the provision 16.
Therefore, it should be not construed to mean that all search in administrative survey can be executed without warrant, but that only the search in administrative survey other than a person’s house can be executed without warrant. According to the provision 16, the search in a person’s house can be done only with warrant, regardless of the search in administrative survey.
From this viewpoint, It could be said that the mail inspection in Case 2 need not warrant, not because it is adminstrative survey, but it is adminstrative survey and the search is not for a person’s house.