This study analyzed the precedents of the Constitutional Court (2018 Hun-Ma 221, 2019.4.11.) regarding autonomous private high school admissions (simultaneous selection clause and prohibition of overlapping application) based on the trust protection principle and whether the right to equality is violated. Examining whether the simultaneous selection clause violates the trust protection principle and infringes the freedom of private school management of the school juristic person revealed that there was a difference in the views of the claimant s trust protection between the constitutional opinion and the unconstitutional opinion. In addition, constitutional opinion pursued the public interest of lowering high school rank and easing competition for entrance exams, while unconstitutional opinion presented the public interest of autonomy, diversity, and excellence in education. Next, following the examination of whether the prohibition of overlapping support infringes on the equal rights of students and parents, the principle of proportionality, a strict screening criterion, was applied. Regarding this provision, the judges of the Constitutional Court considered the diversity, autonomy, and excellence of high school education, which is the purpose of the establishment of private high schools. This study found that a sufficient review is necessary to establish the legal basis for the education system, as the admission process for private high schools plays an important role in establishing the basis for the reform of the high school education system, as it is linked with related policies.