State Sen. Richard Pan, D-Sacramento, center, accompanied by co-author Ben Allen, D-Santa Monica, background, and concerned mothers and their children, answers a question about their proposed legislation requiring parents to vaccinate all schoolchildren, during a news conference in Sacramento, Calif., on Feb. 4, 2015. California enacted some of the nation's most aggressive social policies this year, including Pan's and Allen's SB277, the bill requiring parents to vaccinate schoolchildren.
State Sen. Richard Pan, D-Sacramento, center, accompanied by co-author Ben Allen, D-Santa Monica, background, and concerned mothers and their children, answers a question about their proposed legislation requiring parents to vaccinate all schoolchildren, during a news conference in Sacramento, Calif., on Feb. 4, 2015. California enacted some of the nation's most aggressive social policies this year, including Pan's and Allen's SB277, the bill requiring parents to vaccinate schoolchildren. AP File Photo
State Sen. Richard Pan, D-Sacramento, center, accompanied by co-author Ben Allen, D-Santa Monica, background, and concerned mothers and their children, answers a question about their proposed legislation requiring parents to vaccinate all schoolchildren, during a news conference in Sacramento, Calif., on Feb. 4, 2015. California enacted some of the nation's most aggressive social policies this year, including Pan's and Allen's SB277, the bill requiring parents to vaccinate schoolchildren. AP File Photo