Serving as US state supreme court judge is a demanding and highly-skilled profession, requiring extensive expertise, as well as social and managerial abilities. To prevent judges with lifelong tenure from staying on when age-related issues might interfere with their work performance, many states have introduced maximum age constraints. 

In a paper in the American Economic Journal: Economic Policy, authors Elliott Ash and W. Bentley MacLeod measured the effects of retirement policies on court performance and found evidence that mandatory retirement ages increased the output and legal influence of US state supreme courts. 

Their findings are based on an analysis of all decisions in state supreme courts from 1947 to 1994, combined with citation measures from 1947 to 2012. Citations, especially positive citations, are often seen as an indicator of a decision’s quality or usefulness for other judges, making it a reasonably close proxy for the legal influence of a court.

Figure 2 from the authors’ paper shows event study estimates of what happened to the number of positive citations before and after mandatory retirement reforms across several US states.

Figure 2 from Ash and MacLeod (2024)

The x-axis represents the years before and after the reform, and the y-axis represents the impact on the logarithm of positive citations per court per year. The dashed vertical line indicates the year before the reforms went into effect. The vertical bars are 95 percent confidence intervals.

There was no trend in citations across courts in the years before the reforms. But after the reforms, there is a clear increase in the number of citations, which is sustained over a number of years. Overall, courts implementing a mandatory retirement age saw positive citations increase by approximately 25 to 30 percent on average.

The researchers argue that this boost in productivity is driven in part by replacing older judges with younger ones who have higher performance. They also find that older judges on a court can reduce the performance of younger colleagues, either by increasing their unobserved workloads or by court norms that keep workloads capped at what the lowest-performing judges can handle. 

The authors’ work highlights the positive impact of mandatory retirement policies on the US legal system. Policymakers may want to keep these findings in mind when trying to balance the tradeoff between age-related performance decline and experience.