J-3, r. 3 - Rules of procedure of the Administrative Tribunal of Québec

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17. Any party to a recourse may, with the authorization of the Tribunal and on the conditions it determines, implead a third party whose presence is necessary to resolve the dispute completely.
The Tribunal may, ex officio, order the impleading of any person whose interests could be affected by its decision.
O.C. 1217-99, s. 17.