Political parties, whose main objective is to rule the state by winning elections, must comply with constitutional and legal regulations. Since the sanctions to be applied to political parties that act contrary to these regulations will result in the limitation of political rights, it is very important that they must comply with the principles of proportionality and availability. Although “the closure of political parties” or “state aid to political parties” are among the topics that are frequently subject to academic studies, the issue of “warning”, which is often stated to be unconstitutional because of that it is not subject to constitutional regulation, has not been the subject of academic studies at the same level. The starting point of the study was the idea that it may be beneficial to evaluate the issue of warning sanction in the light of the Constitutional Court decisions in a process where the Constitution and the Law of Political Parties are on the agenda. In the study, the legal bases of the warning sanction, the decision process of the Constitutional Court upon the application of the Chief Public Prosecutor of the Supreme Court of Cassation, the nature of the warning sanction, the constitutionality of the warning sanction, the types of the decision given at the end of the warning application process, the time period for the decision of the warning applications were discussed. In addition, the approach of the Constitutional Court has been examined by subjecting the warning applications to subject-based classification.