This paper uses John Rawls' theory of justice to defend the patent system against charges that it has an unfair effect on access to medications, from the perspective of national and international justice. The paper argues that the patent system is fair in a national context because it respects intellectual property rights and it benefits the least advantaged members of society by providing incentives for inventors, investors, and entrepreneurs. The paper also argues that the patent system is fair in an (...) international context, provided that developed nations take steps to help disease-stricken countries secure internal justice. Fairness in a national or international context also requires that the patent system should include emergency exceptions to deal with short-term inequities. (shrink)