Is Bigger Always Better? On Optimal Panel Size, with Evidence from the Supreme Court of Canada

Abstract:     
The US Supreme Court typically sits en banc. By contrast, it is unprecedented for the House of Lords in the UK to sit en banc; instead, its twelve members are assigned to fixed panels of five to hear the vast majority of appeals. The Supreme Court of Canada, which has nine members like the US Supreme Court, routinely sits in panels of five, seven, or nine justices, depending on the appeal; about half of the appeals are heard by panels of seven justices. This variation in high court practices gives rise to a puzzle. Is a fixed panel size optimal or is there some reason to prefer a system which allows panel size to vary? If panel size ought to be fixed, is the largest possible panel size generally preferable? Should a panel that is a subset of the court's members be deployed, or is sitting en banc better? In this paper, we develop a formal model of the optimal choice of panel size. The model suggests that in the presence of scarce judicial resources, panel sizes can be deliberately adjusted to improve allocational efficiency. Using data from more than 2000 appeals decided by the Supreme Court of Canada from 1984-2005, we show that the Court appears to be using varied panel sizes in a manner consistent with the predictions of our model.

Working Paper Series