Not that evidence analysis, or forensics labs, or even witnesses, are always or even usually wrong. They're just wrong often enough to give one pause about the justice system in general, and capital cases in particular.
DNA Analysis Exposes Flaws in an Inexact Forensic Science – NYTimes.com
Instances of wrongful imprisonment have made clear that microscopic hair analysis, a staple of forensics for years, was not as flawless as people had been led to believe.