The system can make tragic mistakes. Cameron Todd Willingham was executed for setting the fire that killed his children, based on what even the Texas Forensics Science Commission acknowledges was junk science. Modern forensics has shown the fire was accidental, not arson. We’ll never know for sure how many people have been executed for crimes they didn’t commit. As of now, 140 wrongly convicted people on death row have been exonerated. DNA is rarely available in homicides, often irrelevant (as in Willingham’s case) and can’t guarantee we won’t execute innocent people. Capital juries are dominated by people who favor the death penalty and are more likely to vote to convict.