California’s citizen led initiative to legalize recreational marijuana use created a new area for law enforcement to exercise discretionary authority. Unlike alcohol DUI’s—where breathalyzers measure B.A.C. (blood alcohol content) and determine impairment per se —California courts currently rely heavily on officer testimony to prosecute people in DUID (driving under the influence of drugs) cases. Acting as street-level bureaucrats, police must translate California’s new marijuana policy into practical rules on the ground. Using ethnographic methods, primarily participant observation and interviews, I interrogate a topic central to today’s zeitgeist, the public’s concern over police discretion. Specifically, officer behavior and their policing approaches in presently in potential marijuana DUI cases. Understanding how police, in the absence of valid tests and procedures, mobilize the law serves to obtain at the ground level of analysis how police exercise discretion, what presently passes as constituting the body (corpus delicti) of a “normal” marijuana DUI offense, and why the present tendency is the current outcome. As well, beat officers serve as a comparative axis at the floor level of analysis from which to study how the law is socially constructed. This investigation contributes to the social construction of law and contributes to the public understanding of the law, both in marijuana DUI’s and in police discretion. With the normalization of marijuana use in Santa Cruz County, and in relation to the real concerns of inhabitants, there is a collective tendency for police to approach marijuana DUI’s as not “real crime.”