In Robison, the suspect was driving under the influence of alcohol and possibly other drugs, including marijuana.  The officer arrested Robison and read the standard implied consent warnings for breath. Consistent with the practice at that time, Robison was NOT read the warning for THC because no breath test device detects THC, the psychoactive ingredient in marijuana.   

On appeal, the Court of Appeals concluded this was improper.  The COA believed the implied consent allows the officer no latitude in giving the warnings and they must all be provided each time.  Because officers routinely do not read CMV warnings to non-CMV operators, do not read Under-21 warnings to those over-21, the ruling was a significant threat to many DUI cases.  Snohomish County appealed based on a number of contrary cases that permit the officer to exclude warnings irrelevant to the particular suspect.    Andrew Alsdorf (Snohomish County DPA) and Dan Heid (Amicus for WSAMA) briefed the issues for the State.  On review, the State Supreme Court agreed with the State.  Irrelevant warnings need not be provided during the implied consent warnings.    The full opinion is available here: State v Robison SC 2016.pdf