Brain Computer Interface (BCI) technology offers potential for human augmentation in areas ranging from communication to home automation, leisure and gaming. This paper addresses ethical challenges associated with the wider scale deployment of BCI as an assistive technology by documenting issues associated with the development of non-invasive BCI technology. Laboratory testing is normally carried out with volunteers but further testing with subjects, who may be in vulnerable groups is often needed to improve system operation. BCI development is technically complex, sometimes (...) requiring lengthy recording sessions to achieve the necessary personalisation of the paradigms, and this can present ethical challenges that vary depending on the subject group. The paper contributes to the on-going ethical discussion surrounding the deployment BCI outside the specialist laboratory and suggests some tentative guidelines for BCI research teams, appropriate to those deploying the technology, derived from experience on a multisite project. Any tension between deployment and technical progress must be managed by a formal process within a multidisciplinary consortium. (shrink)