Susan Bandes is the Centennial Professor of Law at DePaul University and a 2015 Public Voices Fellow of the Oped Project

In Albert Camus' novel The Stranger, the character Meursault fails to cry at his mother's funeral, an optic that comes back to haunt him in a later murder trial when a prosecutor calls it evidence of his heartlessness.

We judge others by whether they've visibly displayed the right emotions for the situation. But our craving for public feeling also represents an alarming feature of the judicial system: We expect criminals to act remorseful, and their failure to do so can be fatal.

Unfortunately, it is increasingly clear that we don't know remorse - or lack of remorse - when we see it.

When Dzhokhar Tsarnaev was on trial for the Boston Marathon bombings, journalists concluded that he was unremorseful for the grievous pain he had caused based on his "toe-tapping, his beard fiddling," and his "casual affect." The jury cited his lack of remorse as a major factor in its decision to sentence him to death.

Capital jurors are powerfully influenced by a defendant's remorse in the courtroom - it is one of the main reasons they cite for deciding on a death sentence. Even the U.S. Supreme Court subscribes to the notion that a remorseful demeanor helps the court to "know the heart and mind of the offender."

Legal customs in this area derive more from our hearts than from evidence. No matter what the law says on the surface, we care deeply about remorse. We see it as a sign of good character - or a signal that the wrongdoer wants to be a better person in the future.

U.S. District Judge Richard Posner, not usually prone to misty sentimentalism, said that "a person who . . . feels genuine remorse for his wrong . . . is on the way to developing those internal checks" that keep people from committing more crimes.

But there is no firm evidence that a remorseful person is less likely than anyone else to commit another crime. Experts on remorse, including Richard Weisman, author of the 2014 book Showing Remorse, find the relationship between remorse and future law-abiding behavior to be mixed at best.

We have only to think about the cycle of domestic violence - the abuser feels terribly sorry, makes amends, vows to be a better person - and then repeats the cycle.

Some visible emotions, such as shame, actually predict an increased chance that the offender will commit another crime. And there is no evidence jurors can tell shame from remorse.

Judges, like juries, put great stock in visible demeanor - they view it as more genuine than a prepared speech. In a 2015 study, Rocksheng Zhong and his colleagues found that most judges were confident that they could identify sincere remorse, but there was little agreement about what remorse looked like. Some judges said that eye contact was a sign of remorse; others found eye contact was a sign of lack of remorse and disrespect.

The slippery logic of remorse is hardest on juveniles who try to project a tough exterior - a natural defense mechanism that any parent would recognize - only to be judged remorseless and amoral.

The falsely accused may even be convicted, sentenced harshly, and denied parole because they did not exhibit remorse for the crime they didn't commit. Consider the Central Park Jogger case, in which five teenagers were convicted of a rape. In a 1995 decision, the parole board declined to release one of the teenagers, Kevin Richardson, because he "continues to deny his guilt and does not demonstrate remorse for these brutal and senseless crimes." But he was only telling the truth. In 2002, all five men were exonerated after undeniable evidence of their innocence emerged.

Looking for remorse is an instinctive impulse, but there are ways to make sure remorse doesn't become an all-encompassing fetish. To name a few:

Judges can formally instruct juries about the pitfalls of evaluating remorse.

Expert defense witnesses can testify at trial about the perils of reading remorse from facial expression.

Prosecutors can be barred from arguing that a defendant's facial expression failed to demonstrate acceptable remorse.

These are modest and achievable reforms. They are a good first step toward making decisions about life and liberty based on accurate information instead of folklore.