I wouldn't ban the use, I'd just make sure that the use of an eye witness isn't rated too highly. I don't know what would be a fair amount of consideration to give, but I know that people can lie, people can think they saw things that didn't really happen, and people's brains can start filling in the gaps based on information provided, when information is missing. Overall eye witness testimonies aren't super reliable, but they aren't entirely worthless either.

While it is true that eyewitnesses at times are mistaken - they are not infallible - but they are not either totally fallible. At times an eyewitness may be in a position to do a great justice for his society, otherwise he may - perhaps in error, perhaps in malice - do a great injustice to either the individual at trial or, if his testimony is in favor of the defense, a great injustice to society at large. Ultimately, it is the role and the duty of the jury and of the other participants in the court to weigh the verity and the ultimate influence of not only the eyewitness's testimony, but to nuance every particle from which it is comprised: to pry it apart and piece it back together and be absolutely certain that it fits in the frame of the case.