Neurotechnologies that are currently applied to treat a range of neurological and psychiatric diseases were found to have a number of positive side effects on cognitive functioning in healthy individuals. Consequently, these neurotechnologies could in theory be used for cognitive enhancement purposes, for instance, the improvement of eyewitness memory. Improving the process of collecting eyewitness testimony would be of great value and is an example of cognitive enhancement for the common good. In this article, we discuss the epistemological and ethical issues such use raises. These issues are not only critical to using neurotechnologies to improve eyewitness memory, but have a wider scope. By discussing enhancement for a purpose that is not primarily self-regarding or self-serving but potentially benefits the society as a whole, we reflect on the consequences of accepting enhancement for the common good for the acceptability of cognitive enhancement in general.