What is the test for determining whether a drug can be used in a criminal case?

Defendants rely on the unusual case of People v. Ramirez (1952), 113 Cal.App.2d 842, 849-851, 249 P.2d 307. There defendant was on trial for illegal sale of heroin. In evidence were certain capsules which contained a residue of white powder. After the taking of evidence had been concluded, and in the absence and without the knowledge of defendant and defense counsel, the prosecution was permitted to turn the capsules over to a chemist for analysis. The prosecution was then permitted to reopen the case and introduce testimony of the chemist that the capsules had contained heroin. It was held that the court's action was prejudicial error because (at page 851(2) of 113 Cal.App.2d, at page 312 of 249 P.2d) 'All proceedings in connection therewith were secret. Defendant was not notified and thus given an opportunity to object to such action or to participate therein. Defendant was also denied the right to have another chemist present when the test was made.'