DNA testing has emerged as a powerful tool capable of establishing the innocence of a person in cases where organic matter from the perpetrator of a crime (blood, skin, semen, etc.) has been obtained by law-enforcement officials. This organic matter can be tested against DNA samples taken from an accused, or indeed from a convicted, person. If the two samples do not match then they came from different people and the person being tested is innocent.
The Innocence Protection Act became law in 2004 as part of the Justice for All Act. Introduced in Congress by Senators Patrick Leahy (D-VT), Dorothy Smith (R-OR), and Susan Collins (R-ME) early in 2000 as Senate Bill 486, the Innocence Protection Act represents a potentially important step in the protection of prisoners' rights because it would provide prisoners convicted in capital cases access to post-conviction DNA testing. According to Senator Leahy (Hearing on "Protecting the Innocent: Proposals to Reform the Death Penalty," Senate Judiciary Committee, June 18, 2002) as of mid-2002, 101 persons had been exonerated of a capital crime by the use of post-conviction DNA testing.