California Coastal National Monument Expansion Act of 2012

California Coastal National Monument Expansion Act of 2012 - Expands the boundary of the California Coastal National Monument, established by Presidential Proclamation 7264, to include the Point Arena-Stornetta public lands in Mendocino County, California.

Requires management of such lands: (1) in accordance with such Proclamation, and (2) as part of the Monument.

Instructs the Secretary of the Interior to finalize an amendment to the Monument's management plan for the long-term protection and management of the lands added to the Monument under this Act.

Permits the use of motorized and mechanized vehicles in the Monument only on roads and trails designated for their use.

Specifies this Act's effect on: (1) aviation overflights, special use airspace, or military flight training routes; (2) low-level overflights above the adjacent Gulf of the Farallones National Marine Sanctuary; (3) Department of Homeland Security (DHS) law enforcement authorities; (4) the rights of Indian tribes and Indian religious communities; (5) protective perimeters and buffer zones; and (6) livestock grazing.

Requires management of the Monument as part of the National Landscape Conservation System.