The unreliability of eyewitness reports is well known, and, thankfully, the court's reliance on such testimony is changing as resources such as video and DNA evidence become more sophisticated and more accessible. (See the Edutopia.org article "Bearing Witness: DNA Throws the Book at Mistaken Identity.")
Whether you teach history, sociology, psychology, or science, the research into eyewitness testimony can make for fascinating classroom learning. Take a look at these resources:
Articles, Transcripts, Talks, and Research About Eyewitness Testimony
A page on the JFK Assassination Resources Online Web site that features a list of links to eyewitness testimony about John F. Kennedy's assassination, the killing of police officer J.D. Tippit, and the arrest of Lee Harvey Oswald.
"The Problem with Eyewitness Testimony"
An account from the Stanford Journal of Legal Studies of a talk by Stanford University psychology professor Barbara Tversky and Stanford University law professor George Fisher.