Retractions warn users against relying on problematic evidence. Until recently, it has not been possible to systematically examine the influence of retracted research on policy literature. Here, we use three databases to measure the extent of the phenomenon, and explore what it might tell us about the users of such evidence. We identify policy relevant documents that cite retracted research, we review and categorise the nature of citations, and we interview policy document authors. Overall, we find 2.3% of retracted research is policy cited. This seems higher than one might have expected, similar even to some notable benchmarks for ‘normal’ non-retracted research that is policy-cited. The phenomenon is also multifaceted. Firstly, certain types of retracted research (those with errors, types 1 and 4) are more likely to be policy-cited than other types (those without errors, types 2 and 3). Secondly, although some policy relevant documents cite retracted research negatively, positive citations are twice as common and frequently occur after retraction. Thirdly, certain types of policy organisations appear better at identifying problematic research, and are perhaps more discerning when selecting and evaluating research.
