TL;DR: In this article, the authors developed and tested a political model of Court retirements and found that there is an identifiable political element relating to the timing of retirements from the Court.
Abstract: The president's ability to nominate justices to the United States Supreme Court is one of his most powerful tools for advancing his policy goals. To maximize the use of this tool it is important that he be able to determine how reasonable it is to expect a retirement from the Court during his presidency. Prior research is inconclusive as to whether Court retirements are politically motivated. In this study I develop and test a political model of Court retirements. The results from estimating the model using exponential Poisson regression show there to be an identifiable political element relating to the timing of retirements from the Court.