Resumen: This article reflects on the suitability of including non-legal arbitrators in certain investment arbitrations. It presents different mechanisms that have been used in the investment arbitration context to aid legal arbitrators with scientific-technical issues and contemplates the drawbacks of this external competence. After analyzing various sectors in which non-legal experts provide internal competence (international inspection boards, specialized national courts, commercial arbitration tribunals, and inter-state arbitration tribunals), the article concludes that incorporating arbitrators with scientific-technical competence into international investment tribunals on an ad casum basis may not be such a far-fetched idea. Finally, various de lege ferenda proposals that would achieve the common goal of not barring non-legal “judges” from the future US-EU investment court are put forward. Idioma: Inglés DOI: 10.1002/crq.21172 Año: 2016 Publicado en: Conflict resolution quarterly 34, 2 (2016), 189-223 ISSN: 1536-5581 Factor impacto SCIMAGO: 0.21 - Psychology (miscellaneous) (Q3) - Law (Q3)