More than a decade of sustained, vigorous research has resulted in an applied cognitive psychology of eyewitness behvaviour that is a rapidly maturing body of knowledge. Several developments now would police forces to increase the sensitivity, reliability, and fairness of eyewitness memory retrieval. The juror's task of estimating the effects of certain variables on the accuracy of eyewitness report can now be a much more informed one, the relevant research literature now being relatively clear and consistent. Across studies the effect size of a number of these variables is moderate or greater. Equally important has been the consistent failure to document several results that would be predicted from the common-sense intuition of juror and jurist alike.