In December 2008 the newly elected Prime Minister of New Zealand bypassed the agency that negotiates with manufacturers about the cost of medicines and agreed to fund Herceptin for women with early stage breast cancer for a twelve months course of treatment. This paper describes the unfolding of this decision and seeks to explain it in terms of the theory of countervailing powers, which has recently been applied to understand the rapid growth of medicines and the governance of the pharmaceutical industry. We explore the role of various actors in this debate about Herceptin funding, drawing on documentary analysis based on a systematic search of journals, websites and media databases. The case of Herceptin both confirms and questions the propositions of countervailing powers theory. On the one hand the manufacturers of the drug proved to be highly influential in their attempts to get Herceptin funded and were generally supported by consumer groups. On the other hand some scientists and regulators attempted to challenge the power of the manufacturers, with the regulators not showing signs of corporate bias as one might expect. Groups did not, as has been proposed, exert power monolithically, with several groups exhibiting opposing factions. The media, ignored in this literature, are considered as a potential countervailing force in the debate. In the end the government bypassed the recommendation of its regulators, thereby undermining the latter's efforts to act as a countervailing power.