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California State Senate Redistricting

Prop. 40 is a referendum on the California State Senate redistricting plan approved by the California Citizens Redistricting Commission. A "Yes" vote approves, and a "No" vote rejects the new State Senate districts. If the proposition does not pass, the districts will be adjusted by officials supervised by the California Supreme Court.

Official Election Results:

Yes: 8,354,158 [71.9%]
No: 3,258,740 [28.1%]

Pro / Con


Supporters of Prop. 40 believe that the measure will protect the existing state Senate maps drawn by the voter-approved independent Citizens Redistricting Commission. They claim that the existing redistricting plan, approved by the passage of Proposition 11(2008) and Proposition 20 (2010) and the defeat of Proposition 27 (2010), created a fair redistricting process with no legislator input.


Hold Politicians Accountable [Website archived in Internet Archive]


There is no official argument opposing Prop. 40. In January 2012, the California Supreme Court ruled that the State Senate redistricting maps generated by the California Citizens Redistricting Commission pursuant to 2008's Proposition 11 must be used throughout the elections of 2012. After that decision, opponents of Prop. 40 announced they would no longer be campaigning against the referendum.




Redistricting is the redrawing of boundaries for legislative districts to reflect changes in population. Redistricting and reapportionment, the allocation of seats to states, help determine the partisan makeup of our legislative bodies, and strongly affect the representation of ethnic groups and geographic areas within the state. The high political stakes of redistricting and reapportionment have led to recurring struggles over control of the process in California. With the passage of Proposition 11 (2008) and Proposition 20 (2010), the responsibility for determining district boundaries was entrusted to the Citizens Redistricting Commission (California Constitution, Article XXI). Every 10 years, following the national census, the commission undertakes the redistricting process.State-Capitol (photo Wikimedia Commons)

In 2011 the commission certified a set of maps establishing the boundaries for the reapportionment of the Assembly, Senate, Congressional, and Board of Equalization districts. Republican leaders accused the Commission of bias when drawing the Senate boundary lines and formally declared their opposition to the maps for those districts. Both supporters and opponents of the new districts worked to place Proposition 40 on the ballot to decide the issue. In the meantime, proponents petitioned the California Supreme Court to determine the legitimacy of the maps. In Janauary 2012, the court ruled that the Senate maps complied with the criteria set forth in the Constitution. Furthermore, the court ruled that election officials must use the commission drawn maps even if Proposition 40 was placed on the ballot. On February 24, 2012, the California Secretary of State's office announced that the measure had qualified for the ballot.

Proposition 40

With Proposition 40 , voters can approve or reject the Senate district boundaries certified by the Citizens Redistricting Commission. If the measure passes, the Senate district lines will be used until the next redistricting process in 2020. If the measure does not pass, the California Supreme Court would appoint "special masters" to establish new Senate boundaries in accordance with the criteria specified in the Constitution. The court would then certify the new district boundaries, which would be used until the next redistricting process in 2020.

Voter Resources

Voter Resources

Official CA Documents

Official Voter Information Guide

Campaign Finance Information

Cal-Access Check out how much money is being raised and spent to pass or defeat this measure, and where the money is coming from.

Cal-Access Ballot Measure Summary Data Search Select "General 06 November 2012" and "Proposition 040" from the drop-down menus. Cal-Access provides financial information supplied by state candidates, donors, lobbyists, and others.

Nonpartisan Analyses


California Initiative Review - Pacific McGeorge Capital Center for Public Law and Policy.

Maplight: Voter's Edge

League of Women Voters: Pros and Cons





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    Craig and Lou at the ballot box: Proposition 40 -- Director's cut ending