Absolutely fascinating. I recommend reading at least the linked summary of the paper from Marginal Revolution, if not the paper itself;
We leverage the as-if random assignment of nonviolent misdemeanor cases to Assistant District Attorneys (ADAs) who decide whether a case should move forward with prosecution in the Suffolk County District Attorney’s Office in Massachusetts.These ADAs vary in the average leniency of their prosecution decisions. We find that,for the marginal defendant, nonprosecution of a nonviolent misdemeanor offense leads to large reductions in the likelihood of a new criminal complaint over the next two years.These local average treatment effects are largest for first-time defendants, suggesting that averting initial entry into the criminal justice system has the greatest benefits.
… We find that the marginal nonprosecuted misdemeanor defendant is 33 percentage points less likely to be issued a new criminal complaint within two years post-arraignment (58% less than the mean for complier” defendants who are prosecuted; p < 0.01). We find that nonprosecution reduces the likelihood of a new misdemeanor complaint by 24 percentage points (60%; p < 0.01), and reduces the likelihood of a new felony complaint by 8 percentage points (47%; not significant). Nonprosecution reduces the number of subsequent criminal complaints by 2.1 complaints (69%; p < .01); the number of subsequent misdemeanor complaints by 1.2 complaints (67%; p < .01), and the number of subsequent felony complaints by 0.7 complaints (75%; p < .05). We see significant reductions in subsequent criminal complaints for violent, disorderly conduct/theft, and motor vehicle offenses.