Most journalists cover many different topics in their career but some focus on a specific area, becoming specialist journalists, covering particular beats like politics, medicine, science, environment, security and so on. In the case of science, but in other areas too, the job of journalists is to render the specialist expertise of some esoteric group intelligible and relevant to ordinary folk. In doing so, they interpret events and place them in a broader context. In many cases, journalists do this by presenting ‘both sides of the argument’ in order to provide a balanced story and prevent accusations of bias. This is fine in principle but difficult in practice, particularly for science, as it requires the journalist to make a judgement about how credible a scientific claim is and thus how it should be reported. For example, should it be reported in a balanced way, in which two more or less equal sides get to make contrasting claims, as a story about a fringe, maverick or otherwise highly uncertain claim being made but not widely supported, or simply ignored as nonsense and not reported at all? In the UK, the reporting of the MMR controversy arguably adopted the ‘balanced approach’ for too long, thus lending greater credibility to the claims that MMR was dangerous than they deserved according to most members of the scientific community. In the latter stages of the debate these stories were often produced by the general news journalists and not the specialist health or science journalists who, by virtue of what we might call their interactional expertise, no longer saw the claims as credible.