An enduring criticism of international arbitration and its legitimacy is that parties can appoint ‘their’ arbitrator unilaterally, which is by itself contrary to traditional notions of judicial impartiality. As a result, the striking lack of dissents and their asymmetry when they occur – usually by the losing party appointed arbitrator – raises questions over whether arbitrators act independently and impartially in relation to the party that appointed them. This chapter investigates whether a background in civil law, as opposed to common law where dissent is a more familiar phenomenon, could explain the absence of arbitral dissents. Using PITAD data on both dissents and arbitrator background, the author explores this potential causal factor. The findings, that differences in background seem unrelated to frequency of dissents, lends some support to the view that the relationship between an arbitrator and the appointing party is a main driver of dissenting opinions.