Where is the Evidence? Comparing the Effects of Evidence Strength and Demographic Characteristics on Plea Discounts.

Objectives: It is well established that defendants who plead guilty receive reduced sentences compared to the likely outcome if convicted at trial. Prominent theories of plea bargaining posit that the plea discount is determined by the strength of the evidence against the defendant. Research on this claim has produced mixed findings, however, and others have suggested that discounts may be influenced by extra-legal characteristics such as race, age, and sex. To date, there have been few attempts to directly compare the effects of these factors on plea discount estimates. Methods: This study uses a penalized ridge regression to predict counterfactual trial sentences for a sample of defendants who pled guilty. Plea discounts are estimated using each defendant's predicted trial sentence and observed plea sentence. Discount estimates are then regressed on variables related to case evidence and the demographic characteristics of the defendant. Results: Results suggest that increases in the amount of evidence associated with a case lead to decreases in the size of the plea discount. Both main and interaction effects are observed for race/ethnicity and sex, with Hispanic and male defendants receiving significantly smaller discounts than White or female defendants. Calculation of standardized effect sizes further indicates that demographic characteristics exert larger effects on plea discount estimates than evidentiary variables. Conclusions: Plea discounts appear to be influenced by both evidence and extra-legal factors. Legal participants may indeed consider the strength of the evidence when determining acceptable plea discounts, but this alone appears to be an insufficient explanation. [ABSTRACT FROM AUTHOR]