An article published in the Las Vegas Sun raises issues about the control of forensics by police labs and the possiblity of cultural bias.
Subtle biases contaminate forensic findings when scientists answer to cops, researchers find
I have worked on the other side of a lot of cases involving police computer forensics examiners. While I have to mostly agree with the recent report Strengthening Forensic Science in the United States: A Path Forward issued recently, I have not experienced what might be considered to be intentional bias on the part of my law enforcement counterparts.
However, there are other pressures that can create problems for law enforcement examiners, whether they are aware of them or not.
In cases where the investigating officer is also the forensic examiner, there is a greater potential for problems to arise. Especially if challenged in the courtroom.
However, I submit that if there is an issue, having the evidence tested by a qualified defense expert serves to offset any unintentional bias by creating a secondary independent examination of the same evidence.
Probably the most disturbing issue with forensic evidence presented in any criminal case is that it can be admitted without independent testing. This is especially egergious in the "soft" forensic sciences where the evidence is judged by human senses, such as in fingerprints, lip prints, handwriting analysis and tool marks to name a few.
Digital evidence is either there or it is not. Locating that evidence is the challenge presented for computer forensics examiners. Once evidence is located, it is then subject to interpretation. One of the challenges with computer forensics evidence is making sure it is presented in the correct context. And that is subject to human judgement in many cases.