California Constitution
From Conservapedia
The California Constitution is the supreme governing document of the State of California. It contains instructions for almost every facet of state government, and has been amended over 500 times, due in large part to the initiative provision which allows the public (not just the Legislature) to propose amendments to be voted on. Opponents allege that the piecemeal design has created a disaster that makes the state ungovernable.
Even so, it is only the third longest state constitution, behind Alabama (the longest, and most restrictive, as it centralizes power at the state level) and Texas (which strictly limits the power of state government, thus necessitating frequent amendment).