Common mistakes firearm owners make, The Series
1. Firearm Violations in Motor Vehicles:
Law enforcement statistics will confirm that this is the number one reason why otherwise law-abiding California gun owners are arrested. If you are driving with a firearm/s you must make certain all firearms carried in motor vehicles are unloaded; this means you should personally make certain that the firing chamber, cylinder, fixed magazine or any detachable magazine attached to the firearm is empty (detachable magazines attached to the firearm, but containing ammunition may result in arrest, attempted criminal prosecution or the filing of more serious criminal charges).
There is an additional requirement for handguns and registered assault weapons carried in motor vehicles. Handguns and registered assault weapons carried in motor vehicles must be unloaded and must be carried either in the trunk or in a secure, fully-enclosed, locked container, other than the utility or glove compartment. To avoid arrest and attempted criminal prosecution.
I recommend the use of compliant locked containers for all firearms being transported in motor vehicles. The Penal Code lists numerous exceptions to these requirements but do not rely upon them unless you are certain that they apply to your situation.
Disclaimer: The above is subject to change as a result of future court decisions and/or new legislation and is intended only as general information. For advice concerning a specific situation you should contact a qualified California attorney.