> He was arrested and charged with driving under the influence in Solano County, but investigators found no alcohol or drugs in his system. Fairfield resident Joseph Schwab, 36 did test positive for one substance: caffeine.

Such a strange insistence in journalism to use obtuse, inconsistent, useless definitions for the word "drug", often that change within the same article.

Anyway, at the end of the day, if the dude was driving recklessly, which the LEO says he was, then charge him with that. This is a great example of why it doesn't make sense to attach criminal liability to blood/brain chemistry.