Artikel 31

1. Judges of the nationality of each of the parties shall retain their right to sit in the case before the Court.
2. If the Court includes upon the Bench a judge of the nationality of one of the parties, any other party may choose a person to sit as judge. Such person shall be chosen preferably from among those persons who have been nominated as candidates as provided in Articles 4 and 5.
3. If the Court includes upon the Bench no judge of the nationality of the parties, each of these parties may proceed to choose a judge as provided in paragraph 2 of this Article.
4. The provisions of this Article shall apply to the case of Articles 26 and 29. In such cases, the President shall request one or, if necessary, two of the members of the Court forming the chamber to give place to the members of the Court of the nationality of the parties concerned, and, failing such, or if they are unable to be present, to the judges specially chosen by the parties.
5. Should there be several parties in the same interest, they shall, for the purpose of the preceding provisions, be reckoned as one party only. Any doubt upon this point shall be settled by the decision of the Court.
6. Judges chosen as laid down in paragraphs 2, 3, and 4 of this Article shall fulfil the conditions required by Articles 2, 17 (paragraph 2), 20, and 24 of the present Statute. They shall take part in the decision on terms of complete equality with their colleagues.