What are the principles of law applicable to a criminal case?

As noted in the previous section, a trial court in a criminal case has a duty to instruct on general principles of law applicable to the case (People v. Blair, supra, 36 Cal.4th at p. 744.) These principles are those that are "'"'closely and openly connected with the facts before the court, and which are necessary for the jury's understanding of the case.'"'" (People v. Valdez, supra, 32 Cal.4th at p. 115.) A challenge to the propriety of particular jury instructions raises an issue of law that we review de novo. (People v. Martinez (2007) 154 Cal.App.4th 314, 324.)