In the past criminal procedure relied upon confessions and witness statements. However with the progress of forensic science the need of such evidence has been declined. And even more important psychology learns us that human memory is anything but reliable.
Even with good will a witness might fail to recollect events correctly. People forget things, mix memories and so on. And to make things even worse, memories can be manipulated by others (e.g. by law enforcement officers or defense attorneys). No surprise, many miscarriages of justice are due to inaccurate testimonies.
And yet many legal systems still force people to show up as witness. However, we propose the following:
- No one shall be compelled to testify in a court of law;
- But anyone who choose to do so, shall tell the truth;
- Co-defendants shall not be allowed to testify against each others.
The rationale for (1) is to encourage criminal investigators to look for physical evidence. In fact no case should be made in the absence of any substantial physical evidence. As a corollary of this rule, special privileges such spousal privilege could be abolished.
Co-defendants have a clear motive to reduce their own involvement, while blowing up the role of the other participants. Also no one shall be forced to testify against himself, which is inevitable if one has to testify against his co-defendants.