A general approach for predicting the behavior of the Supreme Court of the United States.

Building on developments in machine learning and prior work in the science of judicial prediction, we construct a model designed to predict the behavior of the Supreme Court of the United States in a generalized, out-of-sample context. To do so, we develop a time-evolving random forest classifier th...

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Main Authors: Daniel Martin Katz, Michael J Bommarito, Josh Blackman
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2017-01-01
Series:PLoS ONE
Online Access:https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0174698&type=printable
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author Daniel Martin Katz
Michael J Bommarito
Josh Blackman
author_facet Daniel Martin Katz
Michael J Bommarito
Josh Blackman
author_sort Daniel Martin Katz
collection DOAJ
description Building on developments in machine learning and prior work in the science of judicial prediction, we construct a model designed to predict the behavior of the Supreme Court of the United States in a generalized, out-of-sample context. To do so, we develop a time-evolving random forest classifier that leverages unique feature engineering to predict more than 240,000 justice votes and 28,000 cases outcomes over nearly two centuries (1816-2015). Using only data available prior to decision, our model outperforms null (baseline) models at both the justice and case level under both parametric and non-parametric tests. Over nearly two centuries, we achieve 70.2% accuracy at the case outcome level and 71.9% at the justice vote level. More recently, over the past century, we outperform an in-sample optimized null model by nearly 5%. Our performance is consistent with, and improves on the general level of prediction demonstrated by prior work; however, our model is distinctive because it can be applied out-of-sample to the entire past and future of the Court, not a single term. Our results represent an important advance for the science of quantitative legal prediction and portend a range of other potential applications.
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spelling doaj-art-9083693d372147b598faa6be7be58f882025-08-20T03:04:39ZengPublic Library of Science (PLoS)PLoS ONE1932-62032017-01-01124e017469810.1371/journal.pone.0174698A general approach for predicting the behavior of the Supreme Court of the United States.Daniel Martin KatzMichael J BommaritoJosh BlackmanBuilding on developments in machine learning and prior work in the science of judicial prediction, we construct a model designed to predict the behavior of the Supreme Court of the United States in a generalized, out-of-sample context. To do so, we develop a time-evolving random forest classifier that leverages unique feature engineering to predict more than 240,000 justice votes and 28,000 cases outcomes over nearly two centuries (1816-2015). Using only data available prior to decision, our model outperforms null (baseline) models at both the justice and case level under both parametric and non-parametric tests. Over nearly two centuries, we achieve 70.2% accuracy at the case outcome level and 71.9% at the justice vote level. More recently, over the past century, we outperform an in-sample optimized null model by nearly 5%. Our performance is consistent with, and improves on the general level of prediction demonstrated by prior work; however, our model is distinctive because it can be applied out-of-sample to the entire past and future of the Court, not a single term. Our results represent an important advance for the science of quantitative legal prediction and portend a range of other potential applications.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0174698&type=printable
spellingShingle Daniel Martin Katz
Michael J Bommarito
Josh Blackman
A general approach for predicting the behavior of the Supreme Court of the United States.
PLoS ONE
title A general approach for predicting the behavior of the Supreme Court of the United States.
title_full A general approach for predicting the behavior of the Supreme Court of the United States.
title_fullStr A general approach for predicting the behavior of the Supreme Court of the United States.
title_full_unstemmed A general approach for predicting the behavior of the Supreme Court of the United States.
title_short A general approach for predicting the behavior of the Supreme Court of the United States.
title_sort general approach for predicting the behavior of the supreme court of the united states
url https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0174698&type=printable
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