First, after some discussion about its ambiguity, the Working Group ultimately decided to retain the phrase ‘de jure or de facto’ as it wanted to ensure consistency with the 1976 UNCITRAL Arbitration Rules. The text of article 14 of the Model Law was based on article 13(2) of the Rules, which uses the phrase ‘de jure or de facto’. Like article 14 of the Model Law, article 13(2) of the Rules permits an arbitrator to resign and withdraw from an arbitration proceeding, and allows the parties to terminate the mandate of an arbitrator where it is impossible for him or her to perform his or her functions due to a factual and/or legal impediment.