The “Three-Step Theory” of the German Federal Constitutional Court: The connection with the “Principle of Proportionality” or “Functional Interpretation of Law”

The German federal constitutional court says in its “communal decision law ruling （1979）” that it uses three measures for judging the validity of the legislature’s prediction. But this theory, which is called a “three-step theory”, has two obscure points. The first is how to divide these three measures’ occasion of use. The second is how to interpret constitution in this theory. This article proposes to promote an understanding these two points. Part II analyses the contents of the “communal decision law ruling”. What was fought in this ruling was the constitutionality of the law, which violates human rights moderately. The judge used mild measures in this ruling. Part III analyses two rulings quoted by the “communal decision law ruling”. What was fought in the “pharmacist law ruling（1958）” was the constitutionality of the law, which violates human rights seriously. The judge used strict measures in this ruling. In the “basic treaty ruling（1973）”, the constitutionality of the treaty, which did not violate human rights, was fought. In this ruling, extremely mild measures were used. Part IV analyses where these three rulings cross. These measures are used on the basis of the seriousness of the human rights violation（“principle of proportionality”）. The reason for this is that the court regards the function as “protection of human rights”. So, behind this “three-step theory” is the way to interpret constitution, which attaches importance to the function of national facilities