Strength of Evidence:
- Best strength: DNA
- Weak: Fingerprints, bite marks, bullets, shoe marks.
Problems with forensic evidence:
- Can go against privacy like when people’s DNA just taken from 23AndMe to search for a match
- Evidence could be placed by criminal to implicate someone else
- Evidence can be biased when forensic investigator knows details about the crime like if person is considered suspect by other police.
- Except for DNA, methods can be unreliable
- Forensic investigators don’t have incentive to work with scientists to assess validity and reliability.
How to improve forensics:
- Have more scientific studies underdone to assess reliability and validity
- Send evidence to multiple forensic investigators to get inter-person opinions
- Don’t give away crime details to forensic investigators to bias results
- Don’t word forensic evidence in declarative accusatory terms. Word it using objective statements. For example, the fingerprint matches the one at the crime scene.
## The Conviction Hypothetical
Imagine you have 25 prison inmates and an eye witness that can’t recognize any of them. A prison guard trips and gets knocked out. The prisoners discuss. One inmate walks behind the shed. The rest descend on the guard and kill him. There is a 96% chance you convict a murderer if you convict anyone. Would you convict all 25 people or let them off scoff free?