It has become a widespread concern in recent years that there exist frictions between international investment law and arbitration and democratic governance. In particular, investor-state tribunals can issue awards that may reverse, at least de facto, decisions by democratically legitimated and democratically accountable domestic decision-makers that are deemed pivotal, by those decision-makers, for the pursuit of the public interest of their constituency. The pressure on domestic and regional decision-makers to find responses to such frictions, through treaty-drafting or otherwise, has increased considerably in recent years and arguably has led to a shift in the official policy of traditional proponents of the established system of international investment law and arbitration. This paper explores the potential and the pitfalls of democracy as an argumentative topos informing our view on investment arbitration and the interpretation of international investment agreements, with a specific focus on the allocation of interpretative authority among the contracting parties, investor-state tribunals and state-state tribunals.