Ashkenas, Jeremy, and Haeyoun Park. "The Race Gap in Americas' Police Departments," The New York Times, April 8, 2015.
Thomas Jefferson's 1820 letter to John Holmes
Eckholm, Erik. "Report Finds Slight Growth in Population of Inmates," The New York Times, September 16, 2014.
Wilkerson, Isabelle. "Michael's Brown Shooting and Jim Crow Lynchings Have Too Much in Common. It's Time for America to Own Up," The Guardian, August 25, 2014.
Ewijk, Anne R. van. "Diversity within Police Forces in Europe: A Case for the Comprehensive View." Policing: A Journal of Policy and Practice 6, no. 1 (2012): 76–92.
Background reading on criminal justice structure and process - 
Kadish, Sanford H., Stephen J. Schulhofer. "How Guilt is Established." Chapter 1 in Criminal Law and its Processes: Cases and Materials. 6th ed. Little Brown and Company, 1985. ISBN: 9780316478144.
Clifford, Stephanie. "A Claim of Innocence No Longer a Block to Parole," The New York Times, November 12, 2014.
Swartz, Robert, and Michael M. Baylson, reply by Jed S. Rakoff. "Plea Bargains & Prosecutors: An Exchange." The New York Review of Books, December 2014.
McKinley, James C., Jr., and Al Baker. "Grand Jury System, With Exceptions, Favors the Police in Fatalities," The New York Times, December 7, 2014.
Goodman, J. David, and Al Baker. "Wave of Protests After Grand Jury Doesn't Indict Officer in Eric Garner Chokehold Case, " The New York Times, December 3, 2014.
Video: Giuliani and Dyson Argue Over Violence in Black Communities
Contrasting perspectives on Ferguson:
McFadden, Syreeta. "Ferguson, Goddamn: No Indictment for Darren Wilson is No Surprise. This is Why We Protest," The Guardian, November 25, 2014.
Cassell, Paul. "The Michael Brown Grand Jury Process Was Fair," The Washington Post, November 25, 2014.
More on mandatory minimum drug sentences - Valencia, Milton J. "SJC Chief Seeks Reform in Drug Cases," The Boston Globe, October 16, 2014.
Shear, Michael D. "For Obama, Executive Order on Immigration Would be a Turnabout," The New York Times, November 17, 2014.
Chart Showing Imprisonment Rates vs. Population by Region (PDF) by MIT students. (Courtesy of MIT students. Used with permission.) This chart is using 2013 prison populations found in Table 2 
here (PDF 1.8MB) and state population estimates for 2013 as published by the Census Bureau here.