Both countries have won support from international poverty-relief agencies for their stance. But American officials argue that Brazil is confusing the issue by claiming that the row is about AIDS drugs. The Americans accept that WTO rules let Brazil break patents if it faces a health emergency. What they dispute is a clause in Brazil's patent law that lets it break a patent if the owner fails to make the product there. They fear that this will be copied by other developing countries and will be used to break patents on many other products.
Brazilian officials admit, privately, that their campaign has broader motives.
They yielded to American pressure and introduced patent protection in 1997, eight years earlier than they were obliged to under WTO rules. They also say that the companies broke a promise to invest heavily in Brazil once the patent law was passed. Whatever the rights and wrongs of the case, the victor so far has been Mr Serra. That does no harm to his quest to be a presidential candidate in an election next year. He can present himself as the man who faced down ruthless multinationals and a bullying Uncle Sam to bring cheap medicines to the sick and the poor.