Confronting Label Indeterminacy in Automated Bail Decisions
Organizations: Bernoulli Institute of Mathematics, Computer Science and Artificial Intelligence, University of Groningen, The Netherlands · Department of Legal Theory, Jagiellonian University, Poland
Abstract
Bail decisions present a fundamental challenge for data-driven decision support systems. When bail is denied, the counterfactual outcome of whether the defendant would have appeared in court remains unobserved. As a result, historical bail data embed structural label indeterminacy: future decisions are influenced by past decisions whose outcomes are only partially knowable. Building automated systems on such data risks introducing bias and reinforcing feedback loops. This raises a core question for machine-learning systems intended to assist judicial actors: how should cases in which bail was denied be treated during model development? In a case study of bail decisions from the Unified Judicial System of Pennsylvania, we evaluate five contemporary approaches to handling label indeterminacy across three machine learning models, including a novel label imputation method motivated by the dynamics of bail decisions. Each method relies on unverifiable assumptions, yet all influence the models' predictive behaviour, sometimes even more so than the choice of model itself. Explainable AI analysis further reveals that these effects extend to the models' internal decision-making processes as well. Finally, we consider the notion of label indeterminacy from a legal perspective and assess the legitimacy of these approaches in the context of bail decision-making.
Figures & tables
| Bail Status | |
|---|---|
| Determinate | Posted |
| Forfeited | |
| Revoked (due to FTA) | |
| Indeterminate | Denied |
| Set | |
| Partial Posting |
| ID | Name | Description | Assumption |
|---|---|---|---|
| Correct labels | Includes indeterminate cases without altering their labels. | Assumes defendants who were in pretrial detention would have appeared in court if they were not detained. | |
| Detention-as-failure | Includes indeterminate cases and sets their label to ’fail to appear’. | Assumes defendants who were in pretrial detention would not have appeared in court if they were not detained. | |
| Observed only | Includes only cases where bail was not denied and the outcome is observable. | Assumes missing at random; fails if the choice for the denial of bail is based on the content of the case. | |
| Observed + IP | Trains only on non-denied cases and applies inverse propensity weights to correct for sample bias | Assumes that every case has a non-zero chance of being granted bail (positivity) and that all factors influencing whether bail is granted are captured in the data (no unobserved confounders) | |
| Nearest neighbor | Imputes the labels of bail-denied cases using the most similar cases from the bail-granted sample | Assumes there is a valid similarity metric between bail-denied and bail-granted cases. |
| Method | |||||
|---|---|---|---|---|---|
| Determinate cases | |||||
| Logistic Regression | 10.78 0.44 | 10.42 0.23 | 10.85 0.21 | 10.89 0.22 | 10.70 0.20 |
| Random Forest | 11.37 0.31 | 9.79 0.26 | 11.13 0.17 | 11.06 0.21 | 10.53 0.27 |
| XGBoost | 10.61 0.56 | 10.56 0.30 | 11.41 0.33 | 11.45 0.31 | 10.99 0.32 |
| Indeterminate cases | |||||
| Logistic Regression | 1.25 0.58 | 1.00 0.52 | 0.24 0.50 | 0.60 0.62 | 1.10 0.59 |
Appendix figures & tables1 asset
Supplementary material from the paper’s appendix.
Appendix
| Logistic Regression | |
|---|---|
| Maximum iterations | 2000 |
| Regularization | |
| Random Forest | |
| Number of trees | 500 |
| Maximum tree depth | 8 |
| Minimum samples per leaf | 50 |
Selective Labels
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