Researchers from diverse disciplines - e.g. sociologists, criminologists, political scientists, legal observers, and most recently also psychologists - have repeatedly observed that the unguided use of discretion has frequently led to vast disparity in judicial sentencing, i.e. large variations among sentences given for highly similar offenders and/or offenses. Employing a social-psychological perspective, this controlled experiment demonstrates the disparity reducing effect of discussion in sentencing councils. The report also critically analyzes the validity issues inherent in socialpsychological experimentation on legal decision-making.