Many drivers fail to use a turn signal when they should, but in daytime hours it does not usually result in a traffic stop. The same is not true late at night because police officers are often looking for reasons to stop drivers just to see if they have had too much to drink. Some California counties have specific DUI police patrols active between 10:00 p.m. and 2:00 a.m.
Yet a turn signal is not always legally required for a lane change, freeway exit, or stop in the gas station. California Vehicle Code § 22107 provides:
No person shall turn a vehicle from a direct course or move right or left
upon a roadway until such movement can be made with reasonable safety
and then only after the giving of an appropriate signal in the manner
provided in this chapter in the event any other vehicle may be affected by
Note the phrase “in the event any other vehicle may be affected by the movement.” Unless the lane change is done when another vehicle is close enough by that they driver might be affected by it (e.g., having to brake, slow down, or take evasive action, etc.), then use of the turn signal is not legally required.
In reviewing an identical statute enacted in Arizona, the Ninth Circuit Court of Appeals held that a police cruiser merely being in the vicinity of another other driver was an insufficient basis to require the driver’s use of a turn signal:
“[O]ne finds it highly unlikely that the Arizona legislature had in mind police officers parked at the side of the road looking for traffic violators when it referred to “traffic [that] may be affected by the movement” of an automobile. Ariz.Rev.Stat. § 28-754(A). A reading of that sort would tend to render the “may be affected” language largely nugatory as a practical matter, and Arizona would not be likely to accept that sort of construction of the statute.” United States v. Mariscal, 285 F.3d 1127, 1132 (2002).
So if the police stopped you for not using a turn signal, or you otherwise believe the officer lacked probable cause or reasonable suspicion for detaining you prior to a drunk driving arrest, contact California attorney Paul Burglin who is Board-Certified in DUI Defense and co-authors the two-volume treatise California Drunk Driving Law.