Well, since compelling blood is more difficult now given the USSC ruling last year, more cases are likely to revolve around an officer's training and experience. As a DRE I have been making non-test DUIs for about 16 years and have never, yet, lost a DUI or drug influence case ... ever - even without a test. In some counties in CA they don't even take chemical tests (blood or urine) for non-DUI under the influence (drugs) cases because of the expense, so they rely on the officer's observations.