For kids 6-8 years old, booster seat is required unless your child is greater than 60lbs or over 4'9". Under 6-years they need to be in a booster/carseat regardless of height/weight.
https://www.leginfo.ca.gov/pub/11-12/bill/sen/sb_0901-0950/sb_929_bill_20111004_chaptered.pdf
It goes into effect in January
ETA - What's changed to the current law is that kids under 8 need to be in a booster unless they are over 4'9" (and over 6). I don't see anything in the new bill requiring 80lbs as well, just 60lbs.
Re: PSA - new booster seat law
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