Clear, T. and Frost, N. (2014) The Punishment Imperative, New York, New York University Press
This book was written at a significant turning point in the United States, where rates of incarceration were just beginning to fall from historic peaks – in a country where custody rates are comparatively extremely high. Explanations are tentatively proposed in the effects of the ‘justice re-investment’ movement which was beginning to exert some influence at this point.

Krueger, F. and Hoffman, M. (2016) ‘The Emerging Neuro-Science of Third-Party Punishment’, Trends in Neurosciences, 39, 8, pp. 499-501
A brief article discussing the potential link between blame, punishment impulses and behaviours, and aspects of brain functioning, with the conclusion that further study of the neural mechanisms may be beneficial.

Steffensmeier, D., Painter-Davies, N. and Ulmer, J. (2016) ‘Intersectionality of Race, Ethnicity, Gender, and Age on Criminal Punishment’, Sociological Perspectives, online doi: 10.1177/0731121416679371
One of many sources reviewing sentencing statistics and concluding that there is an imbalance in outcomes which adversely affects minority groups, in general, and young black men, in particular.
(see also, Roberts, R. (2015) ‘Racism and criminal justice’, Criminal Justice Matters, 101, 1, pp. 18-20), for another brief commentary on this issue.