## Facts

- A 10-year-old boy was abducted from a church carnival, sexually assaulted, and then taken to a hospital.
- A physician collected rectal swabs using a sexual-assault kit; police also seized the victim’s clothing containing semen stains.
- The kit was refrigerated, but the clothing was not; over time, the clothing evidence deteriorated.
- Months later, a police criminologist tested the clothing and swabs, but the results could not identify the assailant, in part due to degradation from improper storage.
- At trial, expert testimony indicated that timely testing and proper preservation might have produced results that could have excluded Youngblood as the source.
- Youngblood was convicted in Arizona state court of child molestation, sexual assault, and kidnapping.
- The Arizona Court of Appeals reversed, holding that destruction or loss of evidence potentially helpful to the defense violated due process even without a showing of bad faith.
- The U.S. Supreme Court granted certiorari.

## Issues

1. Whether the Due Process Clause requires the State to preserve evidence that is only potentially useful to the defense.
2. Whether a due process violation occurs when the police fail to preserve potentially useful evidence without bad faith.
3. Whether due process imposes a constitutional duty on police to perform particular forensic tests.

## Decision

- The Supreme Court reversed the Arizona Court of Appeals and reinstated the conviction.
- The Court held that, unless a defendant shows bad faith by police, failure to preserve potentially useful evidence does not deny due process.
- The Court found no due process violation because the record showed, at most, negligence and no suggestion of bad faith.
- The Court also held that police have no constitutional duty to perform any particular scientific tests.

## Legal Principles

- Due process treats known, material exculpatory evidence differently from evidence that is merely potentially useful.
- When evidence is only potentially useful and its exculpatory value is indeterminate at the time of loss or deterioration, a defendant must show police bad faith to establish a due process violation.
- Negligent failure to preserve potentially useful evidence, without bad faith, is insufficient for federal due process relief.
- The Constitution does not require law enforcement to employ specific forensic testing methods or to conduct particular tests.

## Conclusion

Arizona v. Youngblood limits federal due process claims based on lost or degraded evidence by requiring proof of police bad faith when the evidence was only potentially useful, and it rejects a constitutional requirement that police perform specific forensic tests.


Arizona v. Youngblood, 488 U.S. 51 (1988)