Sentencing has become the most important part of a criminal case. Over the past century, criminal trials have given way almost entirely to pleas. Once a case is charged, it almost always ends up at sentencing. And notably, judges learn little sentencing-relevant information about the case or the defendant prior to sentencing and have significant discretion in sentencing decisions. Thus, sentencing is the primary opportunity for the defense to affect the outcome of the case by presenting mitigation: reasons why the nature of the offense or characteristics of the defendant warrant a lower sentence. It is surprising, then, that relatively little scholarship in criminal law focuses on mitigation at sentencing. Fundamental questions have not been explored: Do the Sentencing Guidelines—which largely limit the relevance of mitigating evidence—make mitigation unimportant? Does the extent or type of mitigation offered have any relationship with the sentence imposed?
This Article fills that gap by examining a previously unexplored data set: sentencing memoranda filed by defense attorneys in federal felony cases. By systematically parsing categories of mitigating evidence and quantitatively coding the evidence, I show that mitigation is a central predictor of sentencing outcomes and that judges approach mitigation in a modern way: rather than adhering to the strict, offense-centric structure that has dominated sentencing since the advent of the Sentencing Guidelines in the 1980s, judges individualize sentences in ways that consider the personal characteristics of each defendant, beyond what the Guidelines anticipate. And particular types of mitigation, such as science-based arguments about mental and physical health, appear especially persuasive.
The results have significant implications for criminal justice policy: while my data show that mitigation is critical to judges’ sentencing decisions, both the Guidelines and procedural rules minimize mitigation, failing to encourage both defense attorneys and prosecutors to investigate and consider it. I suggest reforms to make sentencing more equitable, such as requiring the investigation and presentation of mitigation to constitute effective assistance of counsel, easing the barriers to obtaining relevant information on mental and physical health mitigation, and encouraging prosecutors to consider mitigation in charging decisions and sentencing recommendations.