Legal Question in Real Estate Law in California

Re: Private road speed limits enforceable by Association Board?

Traffic laws as such are criminal laws and their enforcement involves three phases: detection and arrest, prosecution, and adjudication. Detection and arrest is normally a police function, but as is well known, citizen's arrests are permissible.

Only in rare cases can anyone other than the People, acting through the district attorney, prosecute a crime. Finally, determining guilt and sentencing (whether imposing fines, causing forfeiture of bail, or jail time) is the role of the courts.

I have never heard of a delegation of the right to impose fines to a private street owner and a quick check of the California codes did not turn up one. (This does not mean it doesn't exist.) Such a delegation of criminal enforcement powers would probably be unconstitutional.

Therefore, the "enforcement" of private-street speed rules in your community is probably a matter of private contract, rather than criminal law "enforcement" and you should take a look at the governing agreements, such as covenants, conditions & restrictions (CC&Rs), road-use agreement or other contract or license which applies to owners' use of common areas including the subdivision's roads.

I can't be 100% sure but this looks like contract enforcement rather than traffic law enforcement.