What is the defense of momentary handling of a controlled substance for the sole purpose of disposal?

8. Included are the defense of momentary handling of a controlled substance for the sole purpose of disposal, against a charge of possession of such a substance (People v. Spry, supra, 58 Cal.App.4th at pp. 1367-1369, 68 Cal.Rptr.2d 691), and the so-called defense of necessity against a charge of escape from lawful custody (People v. Waters (1985) 163 Cal.App.3d 935, 937-938, 209 Cal.Rptr. 661; People v. Condley (1977) 69 Cal.App.3d 999, 1008-1013, 138 Cal.Rptr. 515). Whether either of these defenses properly requires a defendant to prove its underlying facts by a preponderance of the evidence is a question we need not, and do not, reach.