China and India are now able to copy complex biotech drugs used to treat cancer and other diseases, bypassing patents held by pharmaceutical companies in richer countries. This allows cheaper generic versions of drugs to be sold in developing countries, reducing healthcare costs but threatening the profits of brand-name drug makers. However, pharmaceutical firms and their allies in wealthier nations are fighting back against this circumvention of patents, creating a dilemma that mirrors the debate around access to AIDS drugs a decade ago over who should have the right to produce lower-cost versions of life-saving medicines.