Adam Gelb’s comment is spot-on. Cross-national comparisons nearly never acknowledge the significant differences between the states of the U.S.. Such differences actually mirror those in Europe, with a range of imprisonment rates and processes of both divergence and convergence. Comparisons between U.S. states reveal huge differences. They differ widely in their imprisonment rates, and in their crime policies that drive imprisonment rates up or down. Only half of the states in fact adopted three-strikes laws, however those who did hopped on the band-wagon within the first two years, with some neglecting their own requirements of budgetary evaluation and prudence. As states climb down from high imprisonment rates some take the lead like California, Michigan and Texas. While half of the states started to reduce the numbers of prisoners, these numbers were still increasing in the other half. None of these states exceeded the number of 2,000 additional prisoners, which was half of California’s reduction. Were the rich states the first to increase incarceration in the 1970s? California was leading, presumably for a bundle of other reasons which had more to do with actors and mechanisms than with their budget. Texas in 2005 was the first state to shelve prison plans; they did this because they had strict rules against overcrowding in place at the time, which spoke to budgetary prudence rather than to a fiscal crisis or declining income. What about Louisiana? In 2009 the state was among those with the highest increase in prisoners, but in 2012 on the road to close more than 1,500 prison places. If there is any indication of path dependency in its criminal justice system it might be more illuminating to look at its history of lynching rather than searching for civil law remnants.
Looking at differences between U.S. states rather than between the United States and other countries has opened up new perspectives for the penal comparationist. They now focus on actors in criminal justice, their decisions, and the institutional framework which sets incentives and equally constrains their decisions. Just like U.S. states adopt policies from each other less because they are neighbours but because they see themselves as “cultural peers,” so do European states. Regional and supranational systems like in Europe and the European Union and also in Latin America increasingly shape national criminal justice systems and imprisonment. For Europe this implies the abolishment of the death penalty in all member states, decisions by the European courts on the vote for prisoners, or a system of monitoring prisons and detention in member states. European states also are part of a supranational regime of welfare policies and provision, and thus European civil law countries have particular combinations of welfare and penal policies in place, which are absent e.g. in civil law countries in Latin America. Nonetheless, European countries and citizens still widely differ in their welfare regimes, the principles that guide them, and the attitudes that support them, and it is often ignored that communist countries in Central and Eastern Europe had a particular authoritarian type of welfare provision from cradle to grave until 1990. Differences in imprisonment rates seem mostly to be independent from certain types of welfare regimes.
In light of these regional and supranational developments federal systems like the one of the United States are of particular interest to track the processes of the exchange and migration of crime policies, as well as the impact of the federal and supranational levels. I find both perspectives necessary and valuable, the close-up on the U.S. states as well as the cross-border gaze. However for exploring the boom in imprisonment and current process of “de-jailing” a comparison between U.S. states will presumably produce the more important and in-depth insights. Therefore Tiffany Bergin from Kent State University and I have embarked on a project that aims to shed light on exactly this.
Imprisonment is the “back-end” of criminal justice, and finalizes the process of doing justice. It has of course always been related to the “front,” to the safety and security of citizens from crime and its deterrent impact on potential offenders. Consequently the question arises how much imprisonment at the back-end is needed to produce safety at the front end. This perspective is wrong for a number of reasons. In particular it neglects the fact that criminal justice is a process that starts with an encounter with police, and continues with a journey through prosecution and courts. In principle, it would be unreasonable to expect the highest impact or any impact at all from the final act of justice and ignoring all other stages and players. It cannot come therefore as a surprise that the relationship between crime (“front,” we need to measure this as violent crime, namely homicide rates) and imprisonment rates is weak and inconsistent in international comparisons. Consequently, no empirically derived equilibrium between imprisonment and (violent) crime is in sight (I gather that both Mike Riggs and Daniel D’Amico are looking for such a chimera), and as long as this is missing, principles rather than data should guide the use of prison for certain types of crimes and offenders, as it does in civil law countries.
In contrast, research evidence and recent experience in Ferguson and elsewhere have clearly demonstrated the importance of the police at the front end of the law, which sheds further doubt on the link between back-end and front. Tom Tyler from Yale Law School and his colleagues across many countries (including both civil and common law countries) show that people are more inclined to obey the law if they are treated with respect and “fairly” by the authorities. “Procedural justice” increases the trust of citizens in the justice system, and this does not only apply to police, but equally to courts, and finally in prisons, where it greatly improves the relationship between staff and prisoners, as Alison Liebling from the Institute of Criminology at Cambridge University found. Safety and security not only means safety for all citizens, but also from violent abuse at the hands of criminal justice and its representatives.
Civil law countries have highly bureaucratized systems of justice, and a number of them are notorious for their kafkaesque and arcane systems, which result in a slow-down and often standstill of justice. Italy is notorious for this, and as “justice delayed is justice denied,” the trust that its citizens have in justice is at the lowest level among European countries. In Latin American countries with often dysfunctional criminal justice systems, trust levels are even lower, and this significantly encourages vigilante and self-help violence as findings from the Latinobarometro show thus driving violent crime up. In sum, safety and security for citizens cannot and should not be simply related to incarceration rates, but we need to take the whole criminal justice process into account as each part contributes in its own way.
What role for punitiveness among the citizenry? Those who assume that a certain level of punitiveness and time-invariable demand for vengeance is part of the human condition will either build safeguards around the criminal justice system (as in civil law countries) or they will aim at balancing such demands with the sanctions that are meted out. Here certainly our capacity for forgiveness and empathy is ignored which balances our thirst for vengeance. Further, from such a perspective the relationship between criminal law and popular beliefs looks like a one-way street: law is shaped by popular demands rather than vice versa. In fact there is considerable evidence to the contrary. Here is my favorite example: When the Federal Republic of (West) Germany was founded in 1949, the death penalty was abolished in the constitution. At this time and throughout the 1950s the majority of Germans supported the death penalty, however support decreased continuously until the second half of the 1960s when at about two third of the population were in favour of abolition, and thus in agreement with their constitutional law. Both educated middle classes and working classes changed their opinion but in opposite directions. While the educated and middle classes had been in support of the death penalty they now opposed it, while a majority of blue collar and less educated strata of society, who had been against the death penalty after the war (they had suffered most from the extensive use of the death penalty and executions by the Nazi regime) now turned around and supported it. Ever since then there has been little change in the majority opposition to the death penalty.
Is optimism reasonable? In the 1970ies a famous article proclaimed that “nothing works” in criminal justice. This was actually the start of a long period of penal pessimism which saw the rise of incarceration in many countries, and encouraged the punitive worldview that took hold of practitioners and researchers. David Green argues that an era of “penal optimism” has dawned in the United States and across the religious and political spectrum. These signs of hope and optimism include new initiatives like the Second Chance Act, and signals like the visits of the first sitting president and a presidential candidate to a prison. I do not think that I am unreasonably hopeful.
 S. Karstedt 2015. “ Cultural peers and penal policies: A configurational approach toward mapping penal landscapes.” Punishment & Society, DOI: 10.1177/1462474515590890
 S. Karstedt 2014. “Europe as a normative power: Cultural peers and penal policies.” Hungarian Society of Criminology, Proceedings of Criminology, 73: Budapest
 D. Green 2013. “Penal Optimism and Second Chances: The Legacies of American Protestantism and the Prospects for Penal Reform.” Punishment & Society 15(2): 123-146.