By Robert H.
I'm flipping through old The Big Question posts on legal issues, because I'm always interested in smart non-lawyers asking questions about the law, and I came across one I'm surprised none of the readers there were able to answer.
A guest blogger wanted to know why we have a fifth amendment. Why a total right to remain silent? Why not just safeguards that prevent coercive confessions, ie only allowing people to be questioned about their alleged crimes on the stand in a public trial where a judge can oversee the process and the public can oversee the judge?
The main reasons given in the comments over there are 1. Because under outlandish hypotheticals this rule works better, and 2. Because the rule is overprotective in order to account for police and prosecutorial abuse. Point 2 is important and probably explains the historical basis for the amendment.
But in the modern world, there are two other strong arguments for the fifth amendment: 1. A witness's behavior and mannerisms have very large effects on how finders of fact interpret the case. Some people look trustworthy on the stand, some people look untrustworthy on the stand, and this doesn't necessarily correlate with who actually is trustworthy or untrustworthy. This raises the problem of a defendant being forced to give exculpatory testimony and the jury saying "He seems like a liar, I bet he's lying about that testimony. Why would he lie unless he has something to hide? It's now more likely that he's guilty." Worse, they might subconsciously think "That guy's testimony made me dislike him, so now I am more inclined to think he is a murderer because f*** him."
Normally we just have to live with this when it comes to witnesses, but in the case of criminal law, where we have a policy preference against false convictions, we don't want people being found guilty of crimes because their mannerisms or lack of coaching make them look like a shifty witness. So we don't make them give testimony. This is a big reason why the defendant choosing to testify opens the door to the prosecution now being able to question him -- his mannerisms and character as a witness is already out there. It's also a big reason why the fifth amendment is less robust in a civil setting -- the witness can't be convicted by anyone observing his mannerisms at that trial.
2. Humans overrate, both in their conscious reasoning and in their subconscious impressions, the accuracy of human memory. If you force someone to testify it is likely to be relatively easy to poke holes in their story, regardless of whether they are lying, simply because they misremember stuff. This can make them look like a liar and leads to the same problems as above. Again, we just live with the fact that lawyers can dismantle most stories from most witnesses in most cases, but here we are more worried about false positives.
Why do I think these are the big issues? Because these are the two main issues criminal defense lawyers consider when deciding whether or not to put their witness on the stand. It's 1. Can he tell a coherent story? 2. Will he come across as a sympathetic witness? Defense attorneys do not ask how the testimony will look to dispassionate observers who ignore the witnesses mannerisms and account for the fact that he could be misremembering details through no fault of his own. They also don't really worry about exposing their client to the judge forcing a confession at trial, even if that is the historical root of the right.
So, to be clear, here is my hypothetical where the lack of the rule would lead to a worse outcome: A guy is innocent of murder. He is called to the stand and forced to testify. Over the seven hours he is questioned, he sweats profusely, has difficulty answering some questions, sometimes contradicts the evidence and himself, and frequently gets angry.
The defense alerts the jury to possible reasons for this -- he is nervous, this is a very emotional issue for him, human memory is faulty, etc. Nevertheless, on a gut level the jurors find him untrustworthy. The facts that, in their mind, he 1. is a liar, 2. strikes them as an angry person, and . is lying about this particular incident, as if he has something to fear from the truth, pushes them over the edge to conviction.