538 on SCOTUS Predicting

June 27th, 2012

The odds of the mandate’s being overturned have fluctuated some since then, but have risen even further in the past few weeks, according to the market.

Is such a large shift in sentiment justified? In my view, probably not. This may be another case of traders being overconfident about the value of their information, a property which has also been observed in the stock market.

To be clear, the evidence is that oral arguments do have some predictive power in forecasting Supreme Court decisions, according to a variety of empirical analyses from academic and legal scholars. It’s just a question of how much power they have, and how unambiguous the evidence about oral arguments is in any particular case.

These studies found that the side being asked more questions from the bench during oral arguments is more likely to lose the case, since this may indicate skepticism from the court about its position.

No citations to our work, alas.