What is the test for destroying or destroying evidence in a criminal case?

"[A] trial court in a criminal case is requiredwith or without a requestto give correct jury instructions on the general principles of law relevant to issues raised by the evidence." (People v. Mutuma (2006) 144 Cal.App.4th 635, 640.)

As a matter of due process, law enforcement agencies have a duty to preserve evidence that might be expected to play a significant role in the suspect's defense. Such "evidence must both possess an exculpatory value that was apparent before the evidence was destroyed, and be of such a nature that the defendant would be unable to obtain comparable evidence by other reasonably available means." (California v. Trombetta (1984) 467 U.S. 479, 488-489 [104 S.Ct. 2528].) If all a defendant can say about the unpreserved evidence is that it could have been tested and the results might have helped the defense, the defendant must show the police acted in bad faith in losing or disposing of the material. (Arizona v. Youngblood (1988) 488 U.S. 51, 57-58 [109 S.Ct. 333] (Youngblood).) Negligent destruction of, or failure to preserve, potentially exculpatory evidence, without evidence of bad faith, does not violate due process. (Youngblood, supra, 488 U.S. at p. 58.)