In what circumstances will police obtain a warrant for the seizure of methamphetamine from a defendant's home?

In People v. Leichty (1988) 205 Cal.App.3d 914, 252 Cal.Rptr. 669, for example, narcotics officers were called to an airport by a clerk who noticed a strong odor emanating from a package left by defendant for air shipment. After conducting an inconclusive field test, the officers took the package to a police laboratory where it was opened and extensive chemical tests performed on its contents, several used soda bottles filled with a yellow liquid. The tests were positive for methamphetamine. On the strength of the laboratory test results, a warrant was obtained and drugs were seized during a search of defendant's home.