The evidence they provide can be critical in identifying, charging, and ultimately convicting suspected criminals. However, eyewitness testimony is not infallible. No evidence seems more convincing upon its first hearing, yet is more unreliable, than eyewitness identification testimony.

Even the most honest and objective people can make mistakes in recalling and interpreting a witnessed event. There can be no reasonable doubt that inaccurate eyewitness testimony may be one of the most prejudicial features of a criminal trial.

Time and time again, eyewitness testimony has proven to be unreliable, sometimes resulting in the conviction of innocent persons. In response, the criminal justice system has gradually implemented a variety of procedural protections which include jury instructions, line-ups, the suppression of unreliable identifications, etc.

Since jurors tend to put a lot of faith in eyewitness testimony, a mistaken identification defense requires careful planning and execution. A defense attorney's role is to approach the subject of eyewitness testimony with a critical and skeptical eye. The defense must educate the jury about the possibility, or even probability, of mistakes.

Although the eyewitness may make a ''positive'' identification of a defendant, it is imperative that the defense attorney be prepared to demonstrate that certainty is no guarantee of accuracy. Therefore, a goal of the defense is to demonstrate to the jury how an eyewitness can be honestly mistaken, by pinpointing the causes and reasons for the error.

Many jurisdictions have a preliminary hearing or probable cause hearing as a first stage proceeding. Although the Confrontation Clause guarantees do not apply at such a stage, nonetheless in many jurisdictions the complainant and/or an eyewitness will be called to testify. One of the purposes of preliminary examination, aside from discovering potential damaging testimony, is to become familiar with the witnesses, their temperaments, character, demeanor while testifying, and any other important mannerisms.

This information, sometimes as much as the actual testimony, must be previewed before the witnesses are actually called and examined before the jury at trial.

Even though defense counsel can challenge eyewitness testimony, it will be the judge or the jury who will weigh this testimony against other pieces of the evidence to determine what indeed happened at the time and place in question.

There is no denying that eyewitness testimony can be persuasive evidence before a judge or jury, especially in criminal trials. Research has shown, however, that eyewitness testimony can be systematically fallible in ways that undermine the goals of the rules of evidence.

This does not necessary mean that eyewitness testimony is always inaccurate - it just means that there are legitimate grounds (and perhaps reasonable doubt) to challenge a case when the only evidence is eyewitness testimony.