As a growing number of countries implement, or announce plans to introduce, a sugar-sweetened beverage (SSB) tax, this paper explores the public health rationale for such a tax and provides an overview of the international normative and policy instruments supporting the introduction of fiscal measures on sugary drinks. After examining parallels between the legal arguments raised by the food and beverage industry in opposition to SSB taxes and those raised by the tobacco industry in response to tobacco control measures, this paper draws four key lessons that will assist countries to design effective and robust SSB tax measures and counter food and beverage industry opposition: regulatory distinctions in tax coverage should be based on bona fide, evidence-based reasoning; evidence-based measures need to be tailored to a country's public health objectives as part of a comprehensive strategy to address unhealthy diet consumption; procedural requirements and due process should be observed in the drafting and implementation of the measure; and regulatory space exists within domestic constitutions, laws and international trade and investment agreements recognising the sovereign right of states to regulate in the interests of public health.