A Tribunal or arbitration panel may occasionally be trapped by a decision paradox when taking a simple, dichotomous final decision (e.g. accept/reject; condemn/acquit…) on a complex case involving two or more independent issues: the way in which the voting is organized —i.e. either issue-by-issue or by final outcome— may change the collective decision. Furthermore, if a majority vote is taken on the final decision, it may be impossible to base the resulting ruling on a set of reasons supported by a majority of members; but if majority voting is applied on each independent issue, the final logical conclusion from these intermediate findings may be rejected by a majority of members.
Lewis Kornhauser originally discovered this so-called «doctrinal paradox» in the US Supreme Court, without realizing that it was already known to political scientists as the «Ostrogorski´s paradox». The paradox may arise in arbitration panels, particularly in investment arbitration.
In non-arbitration contexts, issue-by-issue voting is frequently deemed preferable over conclusion-based or global judgements. Similarly, a case is made here to supplement the standar majority rule enshrined in Rules of Arbitration with an ancillary «issue-by-issue» voting rule, which might read as follows:
«When the decision on the award depends on the opinions held by arbitrators on two or more distinct issues, the president may split the deliberation into the relevant distinct propositions, take a vote on each one and base the award on the resulting outcomes».
The application of this democratic voting procedure may, paradoxically, occasionally require the final decision to be approved under the president´s sole authority, as allowed, for instance, by article 25 of the ICC Rules of Arbitration and article 35.1 of Spain´s Arbitration Law.