JOSE SERRA, Brazil's health minister, this week took his battle against the United States and multinational drug firms over phamaceutical patents to the World Health Organisation's annual assembly in Geneva. At the assembly, which runs until May 22nd, Mr Serra was due to propose a vote condemning the use of trade agreements to obstruct poor countries' access to cheap medicines. This is aimed at the United States, which in January, at the multinationals' urging, complained to the World Trade Organisation (WTO) about Brazil's patent law. Brazil claims that the involvement of the WTO threatens the country's widely praised programme for the prevention and treatment of AIDS.

Last month Brazil won a similar vote at the UN Human Rights Commission. The United States was the only country of the 53 represented not to support a motion urging governments to refrain from measures that would limit universal access to AIDS drugs. A month earlier, Merck, an American company, had agreed to cut sharply the price it charges Brazil for efavirenz, an AIDS treatment, after Mr Serra had threatened to break its patent. He is making a similar threat against Roche, a Swiss company, over another drug, nelfinavir. Roche has agreed to talk.

Brazil's AIDS programme, which has helped to curb the mortality rate from the illness (see chart), includes free treatment with a cocktail of 12 drugs. The government says importing the two patented products cost 39% of the $303m that it spent on AIDS drugs last year. The other ten, which are not patented in Brazil, are made locally and cheaply. Merck backed down when a Brazilian government laboratory showed it could make efavirenz cheaply, and thus that Mr Serra's threat was no bluff. The lab is now busy copying nelfinavir.

Brazil's victories have been reinforced by the withdrawal last month of a court case in South Africa by 39 firms against a law allowing its government to ignore patents and to buy AIDS drugs from cheap, unlicensed sources. Both countries have won support from international poverty-relief agencies for their stance. “World opinion is on our side,” says Mr Serra.

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 are angry that the United States is now showing “ingratitude” by quibbling over a clause in Brazil's law that it has never even threatened to use. They are also furious at foreign drug firms, for not offering cheap “generic” versions of drugs—for all sorts of ailments—whose patents have expired, even though they do this elsewhere. They also say that the companies broke a promise to invest heavily in Brazil once the patent law was passed. The drug firms insist that they have invested $1.7 billion since 1996.

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.