The Australian federal government recently introduced into Parliament legislation mandating the plain packaging of all tobacco products. Tobacco companies and others have raised various legal concerns with this tobacco control scheme, both at a domestic level in relation to constitutional and intellectual property law, and at an international level in relation to international economic law. Some Members of the World Trade Organization (WTO) have asked questions about the scheme in the WTO's Committee on Technical Barriers to Trade and Council for Trade-Related Intellectual Property Rights. In addition, Philip Morris (Asia) Limited has given notice of an investor-State dispute settlement claim against Australia regarding plain packaging pursuant to the Hong Kong-Australia Bilateral Investment Treaty. This article considers the merits of that claim as well as certain related procedural issues. It also compares Australia's investment obligations with respect to plain packaging under the Australia-United States Free Trade Agreement, as some allegations have been made that plain packaging may be inconsistent with those obligations.