In 1963, the U.S. Supreme Court held in Brady v. Maryland that police and prosecutors are legally bound to turn over so-called "exculpatory" evidence to the defense before trial. Exculpatory evidence is most anything favorable to the defense. It can be evidence that the defendant is innocent, that someone else could be guilty, or that there were mitigating circumstances. Or, it can cast doubt on the reliability of prosecution witnesses.
Matthew C. was charged with possessing 92 grams of heroin after a baggie full of white powder was discovered in his van. The powder allegedly tested positive for heroin in a field test. In reality, it was laundry detergent.
If you've been reading our blog, you know that many common forensic evidence techniques have been called into serious question by scientists. Yet police, prosecutors and judges continue to use or allow these techniques to be used. Sometimes, it seems as if they are used simply because they have been in use for so long. That isn't sound policy.
"Rapid DNA" machines are a new phenomenon in criminal justice. Able to process a DNA sample in just 90 minutes, they're often called "the magic box." The machines are small enough to be used by police departments. Until now, DNA testing has been performed exclusively by forensic scientists in neutral, accredited labs.
"How many cases of innocent people being wrongly convicted have to occur before people realize that there's a very broad spectrum of forensic science?" asks U.S. District Court Judge Jed Rakoff, a former member of the National Commission on Forensic Science.
The basic science behind DNA testing is sound enough. Each individual has DNA that varies as much as one person varies from another. With the right technology, we should be able to compare a DNA sample found at a crime scene with one taken from a suspect.
When Francisco Carrillo, Jr., was falsely convicted of a fatal drive-by shooting, it was the result of an improper eyewitness identification. A Sheriff's deputy brought in the 15-year-old eyewitness, showed him a single photo and said it was their lead suspect.
Recently, investigators in California arrested a suspect in the "Golden State Killer" case. Joseph James DeAngelo, a former police officer, is accused of murdering as many as 13 people and raping 50 women during the 1970s and 1980s.
We have written extensively on this blog and elsewhere about faulty forensic science contributing to wrongful convictions. Numerous instances of crime lab scandals between 2000 and 2008, including multiple instances of fraud and error, resulted in Congress funding an in-depth investigation and review of the forensic science disciplines and related forensic laboratory practice.
ProPublica Illinois, a nonpartisan, nonprofit organization that does investigative journalism, recently published an article about inaccuracies in Chicago's gang database. Police and law enforcement officials routinely cite the gang database when investigating and prosecuting crimes. The database is also used for immigration enforcement, criminal background checks and other purposes.