The Sentencing Disparities Effect of Plea Bargaining

Trial in the Shadow of Bargaining Range – The Sentencing Disparities Effect of Plea Bargaining

* Summary of presentation given on the 6^th of September 2023, at the EUROCRIM2023 conference held in Florence, Italy. The pre-arranged panel focused on the topic of unequal sentencing in the criminal justice system. Experts in the field presented their research findings, including quantitative and mixed methods studies, from the UK, Czech Republic, and Israel.

Photo: Dr. Beatrice Coscas-Williams

“Bargaining in the shadow of the trial” model

In the 1970s, the literature in the fields of law and economics displayed significant optimism concerning the effectiveness of plea bargains and other trial waivers in achieving the desired legal outcomes in criminal courts while also saving time and resources. Some even posited that plea bargains could establish a clear distinction between guilty and innocent defendants (separating equilibrium), with guilty individuals admitting their guilt in plea bargains, while innocent ones would reject such offers.

This classic “bargaining in the shadow of the trial” model illustrates that when both the prosecution and defense closely assess the expected trial outcome, opting for a plea bargain becomes preferable for both parties over proceeding to trial. Furthermore, if the prosecution wishes to secure more plea deals, it simply needs to reduce the price of plea bargains.

Challenging “bargained justice”

Criticism of what is referred as “bargained justice” and the plea-bargaining market, primarily voiced by criminologists, provides empirical evidence that plea bargains are frequently determined outside the shadow of trial, due to factors external to sentencing in Trials such as agency cost, psychological pressures, pre-trial detention, and bail rules.

Our criticism is in within the field of economic analysis of criminal law. With Moti Michaeli, in an article published earlier this year (The Vanishing Trial: A Dynamic model with adaptive agents. Special Issue of Public Choice – Law and Economics from the Public Choice Perspective), we showed that the phenomenon of vanishing trials has endogenous factors, and in a forthcoming paper (Trial in the Shadow of Bargaining Range: The Sentencing Disparities Effect of Plea Bargaining – Theoretical and Empirical Study. Harvard Negotiation Law Review, Vol. 28, No. 2, 2023), Jonathan Hasson and I demonstrate that one of the externalities of this phenomenon is the Widening of Sentencing Disparities in Plea-bargains.

“Trial in the shadow of bargaining” model

The “Trial in the shadow of bargaining” model characterizes plea bargains as a phenomenon of positive feedback loop. It explains how, unlike in other markets, the interaction between Trials and plea bargains, instead of balancing and restraining each other, intensify the demand for plea bargains and raise their price. In short, the resources released in plea bargains are used, at least in part, to strengthen cases that go to trial. As a result, the likelihood of conviction in trials increases, the demand for plea bargains rises, more resources become available for litigation, and the cycle continues until trials disappear. This is a deterministic outcome for any legal system who allows circumventing trial through trial waivers.

Sentencing Disparities widen with rising plea-bargain rate

The “Trial in the shadow of bargaining range” model explains and illustrates how this feedback cycle dynamic leads to a continuous widening of the bargaining range and increased sentencing disparities in similar cases.

When defining and characterizing the bargaining range for plea bargains, one can observe that an increase in demand for Plea-Bargains, expands the bargaining range for them. In short, more resources to trial increases conviction rate and shift the demand for plea bargains. That also rise defendant’s reservation point, the max plea bargain price the most pessimistic defendant is willing to accept (as he become more pessimistic). On the other hand, it decreases the marginal returns for the prosecution resources, his reservation point, and the minimum plea bargain price he is willing to accept. The expansion of the bargaining range enables aggravation of sentencing disparities.

An increase in demand for Plea-Bargains, expands the bargaining range for them

Quantitative Methodology

Fortunately, Professor Oren Gazal-Ayal, who was the doctoral supervisor of both of us, agreed to share with us a research database that he conducted, which included comprehensive data on a specific offense during a period in which there was a significant increase in demand for plea bargains.

To measure and compare disparities over more than a decade, during which changes in sentencing policy also occurred, we defined a resilient measure to such changes, we called Sentencing Ratio (SR), which represents the ratio between the punishment agreed in a plea bargain and the punishment that was expected in trial. The expected trial punishment was calculated using statistical models applied to similar cases that were decided in trials. A Sentence Ratio of 0.9 implies a 10% discount in the expected punishment, while a Sentence Ratio of 0.8 implies a 20% discount.

We then calculated the Variance in Sentence Ratio (VSR) for each year, which serves as a measure for the total disparities in punishment in each period and enabled us to test the hypothesis that VSR positively correlates with the rate of plea bargains.

Disparities in total severity of sanction in plea bargains  and in Trials

Comparing VSR between cases resolved in plea bargains to cases resolved in trials reveals that while the VSR in Trials remains stable with the increase in the rate of plea bargains, there is a positive correlation between VSR in plea bargains and the escalating Plea-Bargains rate. Moreover, VSR in plea bargains was presumably influenced by exogenous changes in sentencing policy, in contrast to the classical “shadow of the trial” model.

Trial Matters!

The normative implication is that trial matters. Trial in a free society is important due to the social roll it serves and values it represents, including the presumption of innocence.  Even though judges may exhibit cognitive biases and cause punishment disparities that might seem unfair and discriminating, these biases, disparities and discrimination are amplifying when there are no trials.

A fair and just trial is necessary to preserve our liberty and ensure compliance with the law. Therefore, judicial reform that includes mandatory evidential review in every criminal case is a must, even if the accused admits guilt and waives their right to a trial.

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Yosef Zohar and Jonathan Hasson

Dr. Hasson is a Research Associate, University of Oxford, Faculty of Law, Centre for Criminology & Oxford Death Penalty Research Unit and Research Associate, Center for the Study of Crime, Law and Society, University of Haifa.