What is the test for a jury to be instructed on the essential elements of an offense?

A trial court must instruct the jury on the essential elements of an offense (People v. Flood (1998) 18 Cal.4th 470, 504) and " ' "even in the absence of a request, the trial court must instruct on the general principles of law relevant to the issues raised by the evidence. [Citations.] The general principles of law governing the case are those principles closely and openly connected with the facts before the court, and which are necessary for the jury's understanding of the case." [Citation.]' " (People v. Breverman (1998) 19 Cal.4th 142, 154.) "A 'criminal defendant is entitled to adequate instructions on the defense theory of the case' if supported by the law and evidence. [Citation.]" (People v. Bell (2009) 179 Cal.App.4th 428, 434.)