Legal system is kinda broken.

FOXNews.com - Straight Talk: DNA Testing and the Legal System - Opinion:

"...Garret found that a variety of factors contributed to the initial wrongful convictions.

False eyewitness testimony was the overwhelming factor (79 percent of the cases), followed by faulty forensic science (55 percent), and false testimony from informants working for the police (18 percent).

In 16 percent of the cases, the defendant actually falsely confessed to the crime. False confessions are common among young and mentally ill suspects, particularly when subjected to harsh interrogation from police.

...Garret found that of the 200 people convicted for crimes for which they were later exonerated, just eighteen were granted reversals by the appellate courts.

Of the rest, 67 had their appeals denied with no written ruling at all. In 63 cases, the appellate court's opinion referred to the defendant's guilt. In 12 other cases, it referred to the "overwhelming" evidence of guilt.

...Keep in mind, these are all cases in which the defendant was later determined to be actually innocent of the crime for which he was convicted. More alarmingly, Garret found in his research of these 200 cases that "even after DNA testing became available, courts and law enforcement also posed obstacles to conducting DNA testing, and then denied relief even after DNA proved innocence."

...The same overeager prosecutors, corrupt or incompetent forensics experts and cops, mistaken eyewitnesses, and indifferent courts that prosecute and oversee these cases also move thousands of cases through the system for which there's no safety net of DNA testing.

If it's this difficult for an innocent person to clear his name in cases where there's science available to deliver a definitive answer, imagine the people now wrongly sitting in a jail cell for drug offenses, theft, or for violent crimes for which there was no available biological evidence—people for whom science offers little hope for relief."