“material” and “exculpatory” evidence. Material evidence is important evidence that’s directly relevant to an issue in the defendant’s case. Exculpatory evidence is evidence favorable to the defendant in that it clears or tends to clear him of guilt.Exactly what evidence is material and exculpatory depends upon the circumstances of the case. But alibi evidence is virtually always material and exculpatory; it includes witness statements that place the defendant somewhere other than the scene of the crime and forensic evidence (like DNA) that tends to show that the defendant couldn’t have committed the crime.
In order to prove that the evidence was material, the defendant must establish that
- law enforcement officers had reason to believe the evidence was exculpatory before they destroyed it, and
- the evidence can’t be replaced by other reasonably available evidence.
Courts can sometimes infer materiality from law enforcement’s actions. For example, the fact that the state normally preserves the type of evidence that it destroyed in the defendant’s case may show that the evidence was material. Similarly, the government testing, using, or intending to test or use the evidence provides a strong indication that it recognized the importance of that evidence.
Proving bad faith
Proving bad faith is tough. It’s not enough that government actors were careless or negligent with the evidence—the defendant must show willful, deceitful, or malicious intent. The government failing to follow standard procedures when it lost or destroyed evidence can support an inference of bad faith. An example of bad faith is an officer throwing away a fingerprint sample showing that someone other than the defendant committed the crime.
There are several possible remedies for defendants who learn during trial that the state violated the duty to preserve evidence. They can ask the court to suppress related evidence, exclude or limit testimony about the missing evidence, or dismiss the case. If the missing evidence doesn’t surface until after a conviction, overturning the conviction and obtaining a new trial on appeal are possible.