Police can use it to solve cases that are years old and exonerate people in prison for crimes they didn't commit. But as DNA testing becomes widespread, some are raising questions about how it's used.
Since DNA was first used as evidence in the American courts, it has become a powerful fighting tool.
That's part of the reason congress is considering legislation that would require everyone detained by police to have DNA samples taken for a national database.
But the opposition argues that collecting DNA from suspects violates a person's Fourth Amendment rights against unreasonable searches.
The National Commission on the future of DNA concluded that by 2010, DNA-typing could bring a revolution in how detectives catch criminals.
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