Passage Summary: Lawyers use DNA to prove their clients weren't at a crime scene, but the author thinks this is a mistake because DNA tests aren't always precise enough to tell people apart.

Conclusion: It is incorrect to clear a suspect of a crime based solely on the fact that their DNA does not match samples found at the scene.

Reasoning: While DNA is unique to individuals, the tests used to analyze it frequently fail to distinguish between different people's samples.

Analysis: The author is confused about the direction of the error in DNA testing. If a test 'fails to distinguish' between two different people, it means the test might mistakenly say they are the same person (a false positive). However, the conclusion is about a 'mismatch,' which would be a 'false negative.' If the test is so imprecise that it lumps different people together, a mismatch is actually even more convincing evidence of innocence, not less. Look for an answer that identifies this confusion between the inability to distinguish samples and the reliability of a non-match.