In CA, open carry of a loaded firearm in public places was banned in 1967 by Governor Ronald Reagan.
What was left was the open carry of unloaded firearms in non-restricted areas and the open carry of a firearm in areas where you can legally discharge a firearm.
A few years ago, the CA UOC (unloaded open carry) movement started open carrying unloaded handguns in non-restricted areas as a way to protest CA's carry laws.
As a response, the CA anti-gun legislators passed a law to prevent that activity.
What Governor Jerry Brown signed into law, bans the unloaded open carry of handguns in public places.
You can still open carry unloaded long guns in non-restricted areas and open carry loaded firearms in areas where you can legally discharge a firearm.
In a recent court case, a judge ruled that CA "may issue" CCW system was legal because a non-prohibited person could open carry an unloaded handgun as an alternative to being granted a CA LTC permit.
Now that unloaded open carry has been banned, it removes that reasoning from preventing "shall issue" CCW reform in CA.