http://www.slate.com/blogs/crime/201...or_one_of.html
this growing scandal is one example of how justice can be skewed, tainted, etc, and is one of the reasons why i am against the death penalty.
locally, we had a couple investigators who were found to have lied about their past, education, training, etc. it brought all their credibility into question, and several convictions had to be tossed because the two were the only two to investigate some crimes.
i can't help but wonder about other labs...and as someone once said about dna evidence, it is only as good as the person reading the results.