For your weekend pleasure reading, I recommend the Tenth Circuit’s decision this week in United States v. Hill, a case that raises the question “What were they all thinking?”
At Stanley Hill’s trial on criminal charges arising from his alleged involvement in an Oklahoma bank robbery, the prosecutor presented expert testimony from an FBI agent who was trained in “special tactics and ways to identify  deception in statements and truths in statements.”
The agent testified about Hill’s post-arrest interview with police, and said that Hill’s answers demonstrated that he was not worthy of belief. For example, the agent said that Hill’s behavior and answers were “common among the criminal element to keep law enforcement at bay” during an interrogation.
This sort of “expert” testimony, which essentially told the jury to disbelieve Hill, is so obviously improper, said Judge Carlos Lucero, that it warranted reversal under the plain error rule even though defense counsel did not object.
In sum, a prosecutor presents clearly improper testimony, defense counsel doesn’t object, and the trial judge lets it happen. Again, what were they all thinking?