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.