Evidence is not always what it might seem. That is true even when the case seems to favor the state.
Certain sources or treatments of evidence might call its validity into question. Some recent news items have underlined that fact.
DNA evidence in criminal cases
One notable case in the high Texas courts has to do with DNA evidence. The person convicted might have been the subject of discrimination, specifically suspect bias, during the processing of the evidence.
Both an independent laboratory and the police department’s lab reviewed the evidence. Shortly thereafter, the police lab shuttered after a state investigation uncovered rampant mistakes and widespread bias.
Other types of cases
Cases involving crimes such as burglary might not have DNA evidence. However, they might have physical evidence, such as clothing fibers or fingerprints. It is important to the defense that none of the evidence has any bias or fault in the way the state treats, collects or presents it.
In the courtroom, both the defense and the prosecution must build logical arguments based on all of the available facts. If the facts are in error, then the conclusions probably will be too.
The defendant versus the state
Due to the nature of criminal investigations, it is altogether possible that the prosecution might have processed the majority of the physical evidence in a case. After all, it is the police department and other law-enforcement agencies that collect objects, take photographs and so on.
In this context, the state usually presumes that its employees and contractors process the evidence responsibly. It is up to those defending against charges to call that presumption into question.