Sarena Straus writes about the dangers of jurors judging the demeanor of a witness and deducing truthfulness:

As a prosecutor I learned that there is no pattern to how people grieve or react to trauma. In fact, the bulk of my voir dire often focused on whether the jury would hold it against the victim if they did not cry. In my experience, most rape victims did not cry on the stand and often they had a very flat affect while testifying.

She also points out that this applies to those who are accused of crime as well:

The other thing I learned is that people do hold it against victims and defendants when they behave in a way that the juror thinks they themselves would not behave. They think, “If I was raped, I would cry,” or “If my husband died, I would not have a party.” The truth is that you never know how you will behave when you have been traumatized or you are grieving.

Good points. And defense lawyers need to be especially aware of covering this sort of “evidence” in jury selection, as Sarena points out.

If you remember the Darlie Routier case, several jurors said the strongest evidence was the videotape of the family having a birthday party and using silly string four days after the murders. They just knew they wouldn’t have done that, so they convicted her…