The second paragraph of Article 66 of the Pension and Disability Insurance Act determines that the insured persons determined in Article 34 of the Act acquire rights from disability insurance only in cases of the I or II disability categories. This provision is inconsistent with the general principle of equality before the law determined in the second paragraph of Article 14 of the Constitution, inasmuch as it refers to persons who voluntarily joined compulsory insurance system on the basis of the seventh indent of the first paragraph of Article 34 of the Pension and Disability Insurance Act and chose insurance coverage for all types of insurance, as there exists no sound reason deriving from the nature of the matter for their different treatment. The second paragraph of Article 66 of the Pension and Disability Insurance Act, which determines that the insured persons determined in Article 34 of this Act acquire rights from disability insurance only in cases of the I or II disability categories, whereby it limits the acquisition of rights from disability insurance to only one criterion, i.e. the manner of joining compulsory insurance system, entails an interference with the right to social security determined in the first paragraph of Article 50 of the Constitution. Due to the fact that persons who voluntarily joined the compulsory insurance system in accordance with the seventh indent of the first paragraph of Article 34 of the Pension and Disability Insurance Act and chose insurance for the narrower scope of rights, whereas most of the time before that they had compulsory or voluntarily insurance coverage for all types of insurance, are not ensured any right from disability insurance in the event of the III disability category, and therefore the interference is excessive.