Trombetta-Youngblood Motion

Although the prosecutor does not have a duty to collect evidence helpful to the defense, if it comes into their possession, they have a duty to preserve material, exculpatory evidence.  Arizona v. Youngblood (1988) 488 US 51; California v. Trombetta (1984) 467 US 479.  The prosecutor can be sanctioned with a Trombetta or Youngblood motion for violating the Due Process Clause.
 
The defendant can prove the prosecutor either acted in bad faith by destroying or failing to preserve the evidence. In a bad faith case, it need only be shown that the evidence may have exonerated the defendant. The exculpatory value of the evidence must be clear prior to having been destroyed or lost. Also, the evidence must be so significant in exculpatory value that it cannot be obtained otherwise.  
 
The Supreme Court in Youngblood distinguished Brady on the grounds that once exculpatory evidence is permanently lost, it is nearly impossible for the court to assess the value of material lost.   If proven that the prosecutor failed to preserve exculpatory evidence, sanctions are based on the proven facts of the case, which vary from exclusion of evidence to dismissal of the case.  A court may also allow a defendant to argue to the jury the fact that the lost evidence vindicated the defendant. This motion is typically made at trial before the evidence is introduced and after a jury has been selected. If the motion is made pre-trial it is not necessarily binding on the trial judge. The hearing on this motion is the same as to admissibility of evidence (see discussion above on Evidence Code 402). It is common for defense counsel to move for a protected court order for inspection and testing of evidence that is in the possession of the prosecutor.  It takes skillful defense counsel to determine what evidence may be missing or have been possibly destroyed. Walk Free Law works with forensic experts and/or private investigators to paint a better picture of the missing pieces.
 
There is considerable case law on whether or not the denial of a Trombetta Youngblood motion can be made after a guilty plea because the question relates to guilt or innocence and therefore the issue does not survive a guilty plea. However, in conjunction with other suppression motions under 1538.5 for unlawful seizure of evidence, the issue may be preserved.   For example, in a case involving assault with a deadly weapon by use of a car, if the prosecution fails to preserve the original condition of the car, this may warrant a Trombetta Youngblood motion because it would be clear to the government that the car would have potential exculpatory value in its original state. Without the truth of the physical evidence, relying on sworn testimony turns into a credibility contest.  Critical pieces of evidence, such as a knife in an assault case, must be preserved.  Gross negligence or recklessness by the prosecution can amount to bad faith when critical evidence is lost.  Even if a court finds that the destruction or loss of evidence does not impact due process rights to warrant dismissal, it may still fashion other relief such as suppression or appropriate jury limiting instructions.