Brian Morrisey, of Active Transportation Alliance, authored an article titled, "Be an Effective Crash Witness." Brian interviewed me for this article. I thought it an interesting and worthy topic. If you have time the article is worth a read. Brian touches on a number issues that lawyers face when trying to locate or speak to a crash witness.
Lawyers often have a hard time locating witnesses after the fact. Sometimes witnesses believe that police have their name and contact information, however, we rarely see witnesses listed on a police report. For that reason it is important that the victim takes witness contact information themselves; DO NOT rely on the police. Sometimes a victim is unable to take down witness information themselves. In such an instance, the witness should give their contact information to the parties of the crash. If they can't give their information to the parties involved they might be able to get contact information on the victim and then follow up later.
Even when we can locate a witness, they often refuse to cooperate. It never ceases to amaze me how insensitive people can be after witnessing an accident. It is my experience that a negligent driver will almost always lie in situations where it is their word against the victim's word. In such an instance the independent witness is of paramount importance.