The court was hearing arguments in Peugh v. U.S., which asks whether the constitutional bar against ex post facto laws is violated if a defendant’s prison time is determined under federal guidelines in effect at the time of the sentencing, when that would lead to a longer sentence than the guidelines in effect when the crime took place.

The discussion was dominated by hypotheticals aimed at determining what kinds of statutory changes would trigger the ex post facto rules and which would not. It evolved into a discussion of just how much deference federal sentencing guidelines are given in the wake of the 2005 decision in U.S. v. Booker, which made the once-mandatory guidelines advisory. If new guidelines were so advisory that they could not be viewed as a hard-and-fast change in sentences, then perhaps they were not ex post facto changes in punishment.

Making that point, Alito said, "I think there’s a fair chance as time goes by, we’re going to see fewer and fewer sentences within the guidelines. As judges who began their careers during the mandatory guidelines leave the bench, new judges come in who never had to deal with the mandatory guidelines."

The Trenton native continued, "I’m told that in the Eastern District of New York now, only 30 percent of the defendants receive within-guidelines sentences."

Sotomayor, a one-time district court judge in the Southern District of New York, interrupted to suggest that was nothing new. "You’re assuming that’s changed over time," she said with a smile, directly addressing Alito.

Alito, formerly a judge on the U.S. Court of Appeals for the Third Circuit, sniffed, "Well, when I was on the court of appeals we thought it was our responsibility to ensure the district courts were complying with the Sentencing Reform Act. That might not have been true across the river, but…"

A reply from Sotomayor, who sat on the Second Circuit, ended the discussion. She said, "It wasn’t."

Tony Mauro can be contacted at tmauro@alm.com.