A party is not merely an object of investigation, nor one who must simply wait for the court's gracious disposition; based on its status as a subject of the litigation, it is recognized as having various procedural rights. In Japan, these rights and powers that a party is recognized as having in procedure by virtue of its status as a subject of litigation are grasped as a whole and called "tōjisha-ken" (party rights). This became a single unified concept because the rights a party holds are not unrelated to one another but are connected as a whole from the perspective of realizing procedural justice, and the need for such a concept is recognized. In short, party rights are the collective term for the various procedural rights a party has in its status as a subject of litigation when undergoing a civil trial. They can be seen as the party's procedural rights or rights of participation, and guaranteeing party rights is called procedural guarantee.

The specific contents of party rights created under the Civil Procedure Act include: the right to apply for designation of a date, as a right to monitor the progress of proceedings and to receive a speedy and fair trial; the right to receive notice of dates; the right to receive service of the complaint and the judgment; the right to ask questions and the right to object regarding litigation procedure, as rights to supplement and correct deficiencies in the court's conduct of the proceedings on hearing dates; the right to apply for transfer and the right to apply for exclusion and recusal (Civil Procedure Act Articles 41 to 43, etc.); the right to prove and the right to inspect and copy the litigation record (Civil Procedure Act Articles 157 and 162); the right to be heard, which gives the opportunity to apply for a judgment and submit litigation materials; the right to state opinions on the issues; the right to specify and dispose of the subject matter of the suit; and the right to appeal against an unfavorable judgment.

The principle of party presentation and the parties' respective roles are closely related. Looking at what usefulness establishing the concept of party status has in civil litigation: first, the concept of the party's role serves not only as the criterion dividing contentious cases from non-contentious cases, since party status is more thoroughly protected in contentious civil cases while that protection is insufficient in non-contentious cases, but also as a limit on the trend of turning litigation into non-contentious proceedings; and second, it is very useful in explaining the justification for res judicata affecting the parties. Therefore, where party status, that is, procedural fundamental rights, has not been guaranteed, the conclusion that the judgment is void or must be set aside is drawn. Case law also affirms the existence of procedural fundamental rights, and where a judgment was rendered by fundamentally infringing them, damages for tort can be claimed even without a retrial.

In litigation, the parties have equal status, and their roles and opportunities in the litigation are equally guaranteed. This principle of equality of the parties is also a requirement of our legal order as a whole, as in Article 11 of the Constitution. The significance of today's discussion of party rights, in an era that is no longer authoritarian, lies largely in the point that parties should be treated not simply as objects of procedure but as subjects of litigation who actively participate in it, and that their party status should be respected.

For reference, the material states that ex officio examination of evidence is in principle prohibited, but Article 292 of the Civil Procedure Act allows it supplementarily, providing that the court may examine evidence ex officio where it cannot form a conviction from the evidence applied for by the parties or where it otherwise deems it necessary. In addition, as devices that supplement the principle of party presentation, there are the right and duty to request clarification under Article 136, so the court can ask a party to clarify an unclear assertion. Also compare procedures in which the inquisitorial principle is strengthened, such as family litigation and parts of administrative litigation.