A third person who is legally interested in an action between two parties may, for the purpose of supporting one of them, intervene in the action while it is pending.
Intervention may occur jointly with appeals from judgments, appeals from rulings, or any other act of litigation.
A third person who is legally interested in a final and binding judgment in an action between two parties and who has intervened in such action, may initiate a rehearing action for the party supported.

A motion for intervention shall be filed along with intervention pleadings in the court where the intervened action is pending.
Intervention pleadings shall indicate the following matters:
1.The action intervened and its parties;
2.The legal interests of the intervener in the action to be intervened;
3.The statement of intervention.
The court shall serve the intervention pleadings on all parties.

Except where a party had conducted oral argument without objecting to the intervention, any party may move the court to deny a third-party motion for intervention,
An interlocutory appeal may be taken from the ruling on the motion provided in the preceding paragraph.
An intervener may conduct acts of litigation before the ruling denying the motion for intervention becomes final and binding.

Except for acts that contradict the acts conducted by a supported party, an intervener may conduct all acts of litigation for the supported party according to the phase of litigation at the time of intervention.

Article 56 shall apply mutatis mutandis to all cases where the claims of an action must be adjudicated jointly with regard to the intervener and the party supported.

An intervener may not dispute the correctness of the decisions made in the action against the supported party, except where the intervener has been denied a means of attack or defense either due to the phase of the litigation at the time of the intervention or by an act of the party supported, or where the supported party has willfully or through gross negligence failed to employ certain means of attack or defense unknown to the intervener.
The provisions of the preceding paragraph shall apply mutatis mutandis to the case where the supported party asserts the same dispute against the intervener.

With the consent of both parties, the intervener may assume the action on behalf of the supported party.
When the intervener assumes the action, the supported party will be deemed to have withdrawn from the action. The judgment of the action will have binding effect upon the withdrawing party.

While an action is pending, a party may notify a third party whose legal interests will be adversely affected if such party is defeated.
The notified third person may make further notification to another person.

Notification of an action shall be made by a pleading indicating the reason and phase of litigation reached, and shall be submitted to the court to be served by the court upon the third party.
The notification pleading provided in the preceding paragraph shall also be served upon the opposing party.

The notified person is deemed to have intervened in the action at the earliest time when intervention is available notwithstanding his/her failure or delay to intervene. The provision of Article 63 shall apply mutatis mutandis.

The court may, at an appropriate time prior to the conclusion of oral-argument in the first or second instance, serve a written notice of the action and the phase reached to a third party who is legally interested in the outcome of such action.
The third party notified in accordance with the provision of the preceding paragraph may file, within five days of service of the notice, the motion provided in the first paragraph of Article 242.
Wherever the third party notified in accordance with the provision of the first paragraph is qualified to intervene in accordance with the provision of Article 58, the provision of the preceding Article shall apply mutatis mutandis.