Third party intervention by joining dispute is is a procedural law institute which, according to the law or due to the nature of the legal relationship, a final judgment rendered in litigation to which it is joined applies as equally as to the main party. The Civil Procedure Act prescribes this institute in one provision, and in practice it causes many doubts. The legal interest of a third party intervener by joining dispute is manifested in the fact that the legal effects of the judgment will apply equally to it as well as to the litigant it joined. Because the final judgment applies directly to it even when it does not enter into litigation, a third party intervener by joining dispute is authorized to submit an extraordinary legal remedy even if it has not entered into litigation before the final judgment has become final. Thus, third party intervener by joining dispute is able to take all litigation actions like the party itself, and in the event when the party and the intervener took the same action with the opposite legal effect, the more favorable action will be valid. By interpreting the provisions of substantive law, the courts decide when a person who has joined the litigation will have the status of third party intervention by joining dispute. In the doctrine, there are divided views on which litigation actions can be undertaken by a third party intervener by joining dispute, and priority should be given to the understanding that has its foundation in the principle of the right to be heared before a court. The paper is, therefore, about the court's decisions on the relationships in which the institute appears, the position it has in litigation, its difference in relation to the compulsory joinder of parties, the actions it is authorized to undertake and the effect of finality of the judgement on it.