What is the current state of the law on the test for evidence that the substance was methamphetamine?

But later cases emphasize that proof of the nature of a substance may be shown by circumstantial evidence. (People v. Palaschak (1995) 9 Cal.4th 1236, 1241-1242.) And there is no strict bar against evidence from users. (People v. Chrisman (1967) 256 Cal.App.2d 425, 433-434 ["Although the teetotaller would not be expected to distinguish between bourbon and scotch, once a person imbibes regularly, his opinion on that subject should be relevant, and, under the general rules, be weighed in the light of his experience"].) Here, the evidence shows it was more likely than not that the substance was methamphetamine.