Driving on any public roadway, every mile or so, there are black and white signs telling you what speed you can drive. How do the regulatory signs get to tell you what to do?
California’s speed limit laws are codified in the vehicle code, which establish the different speed limits. There are 2 types of speed limits in California: basic speed (CVC 22350) and maximum speed (CVC 22349).
BASIC SPEED LIMIT
Basic California speed limits in the state of California are mandated by statute to be set: (1) at or below the 85th percentile operating speed (as determined by a traffic and engineering survey) this is the speed which no more than 15% of traffic exceeds; or (2) the prima facie limits mandated when certain criteria are met as described in the vehicle code. These criteria include school zone, alleyway, and residential area.
The theory behind California’s 85th percentile statute is that, as public policy, most of the drivers should be seen as lawful, and limits must be practical to enforce. Thus, 85% of the drivers will go the safe speed given the circumstances without being told the speed limit. However, there are circumstances where motorists do not tend to process all the risks involved, and as a mass choose a poor 85th percentile speed. This is analogous to the population getting to set the speed limit but including an engineering expert to override the population’s decision with justification.
MAXIMUM SPEED LIMIT
Many California speed limit signs are identified as a “maximum speed” limit. These are found on Freeways and highways. When the Federally enacted National Maximum Speed Limit law was created, California was forced to implement a new legal signage category, “Maximum Speed”, to indicate to drivers that the above mentioned Basic Speed Law does not apply for speeds over the federally mandated speed cap; rather, it would be a violation to exceed the fixed maximum speed indicated on the sign, regardless of whether the driver’s speed could be considered “reasonable and prudent.”
As a California criminal defense lawyer, I’d like to note that a driver can still receive a California traffic ticket for violating the basic speed law even if their speed is below the “maximum speed limit” if road, weather, or traffic conditions make that speed unsafe. However, because the Basic Speed Law establishes prima facie limits, not absolute ones, we can defend against such a citation for speeding “by competent evidence that the speed in excess of said limits did not constitute a violation of the basic speed law at the time, place and under the conditions then existing,” per section 22351(b) of the California Vehicle Code.