Diverging from the Shadows: Explaining Individual Deviation from Plea Bargaining in the "Shadow of the Trial"

The “shadow of trial” theory (“SOT”) assumes that individuals make plea decisions based on the probability of conviction at trial (“POC”) and the possible sentence if convicted at trial (“TS”). Although SOT has been generally successful in forecasting plea decisions at the aggregate level, there is still wide variation in plea decisions at the individual level for which SOT does not account. This article analyzes numerous variables to determine when defendants will either adhere to or digress from the SOT model. Because SOT is, at its core, a mathematical theory based on probabilities, the study specifically focuses on how mathematical skill level influences the plea decision. The results indicated that, although POC and TS are the primary elements of SOT, POC has the most significant influence on adherance to SOT. Where POC was the highest (90%), defendant-participants were significantly more likely to adhere to SOT than participants with low POC (10%).  However, it is notable that plea willingness was high across all POC conditions, which implies that individuals with low POC and high plea willingness do not align with SOT predictions. Mathematical skill level positively correlated with SOT adherence, indicating that SOT assumes individuals possess a certain mathematical skill to accurately determine probabilities in making a plea decision. These findings indicate that SOT may not provide the most accurate predictions for defendants’ plea decisions at the individual level.

“[I]ndividuals may not interpret probability in the way predicted by the shadow model, and as such their expected trial outcomes (if they are calculating such outcomes) will likely differ from those of the shadow model, particularly when conviction probabilities are extreme in either direction. . . . [T]he shadow model seemingly assumes that individuals engaging in plea bargaining know their conviction probability and potential trial sentence (or are provided with educated predictions from their attorneys), and can then use those values to accurately calculate their trial value. Our results raise questions about this assumption and the possibility that individual deviation from the shadow model may, in part, be due to a lack of ability to perform the mathematical calculations required by the model.” p. 338