Causes of Wrongful Convictions in Philadelphia

• Withholding or destroying favorable evidence (evidence that might give the defense an advantage at trial) or exculpatory evidence (evidence that either identifies another individual as the perpetrator or excludes the defendant as a possible perpetrator).
• Fabricating evidence, including planting evidence on an arrestee or at the scene of a crime.
• Coercing false confessions from a defendant through intimidation, physical violence, threats against a suspect or their family and friends, or conduct that could amount to torture, such as depriving a suspect of food, water, sleep, etc.
• Improperly influencing witnesses, such as explicitly or implicitly coaching witnesses to make an identification or give certain testimony, or coercing witnesses to give testimony through threats of criminal or civil action against a potential witness.
• Fabricating false or misleading testimony, typically through the use of co-defendants or jailhouse informants, who are offered leniency in their own criminal cases in exchange for providing testimony that will implicate another defendant. Unfortunately, that gives informants or cooperating defendants an incentive to lie, and sometimes investigators or prosecutors are aware of the unreliability or outright falsity of such testimony.
• Perjury by investigating law enforcement officers.
• Prosecutorial misconduct, including hiding evidence, improperly coaching witnesses, making false representations in court, or attempting to sneak inadmissible evidence, testimony, or argument in at trial.
• Shoddy expert testimony, where “experts” provide an opinion or forensic testimony based on untested or disproven scientific principles, or where the results of forensic testing are misrepresented or exaggerated. In recent years, previously widely used forensic testimony like hair or bite mark analysis has been called into question or even ruled as unreliable and inadmissible by many courts. Much of this testimony was given by individuals with dubious qualifications who were willing to offer expert testimony that benefitted the state, in exchange for payments of hefty expert fees.

Other non-misconduct causes of wrongful convictions include:

• Eyewitness misidentification, where an eyewitness makes an honest mistake in their identification of a perpetrator or their recollection of a criminal event.
• Forensic testing errors, where unintentional errors during the laboratory testing process produce inaccurate results.
• Poor legal representation, as criminal defense attorneys can make mistakes or oversights in preparing and trying a defendant’s case. Public defenders are often prone to errors in representation as many, although well-intentioned lawyers, may lack the necessary experience or are overworked due to heavy caseloads.
• Judicial errors, as judges may fail to notice errors or misconduct during the trial that should call for correction, or they may make legally erroneous rulings on evidentiary or other issues that ultimately affect the outcome of the trial.