Unlike Chapter VII of the Indian Evidence Act,[1] which codifies the burden of proof, there is no proper codification of the rules for the same in international law. Investor-state arbitration is a special form of dispute resolution involving arbitration between a foreign investor and a host state. Since it involves a sovereign state as one of the parties, arbitrators exercise a public function, and thus they must carefully employ the law of evidence to the dispute. Further, it is interesting to look at the law of evidence from an arbitration perspective. Claims filed by Claimants are almost always responded to by counterclaims by Respondents, causing a continuous shift in both the onus and the burden of proof. This paper picks up from the lacunae of conventional laws or rules governing the burden of proof in Investor-state arbitration. It looks at the exceptions to the generally accepted norms of burden of proof and analyses them specifically from a jurisdictional angle.