Although the Plastic Bag Ban started on March 16, 2011, it will not be strictly enforced until September 1, 2011. The six month grace period is so stores can educate their customers on the ban and encourage reusable bag use. After, the official start date it will be 10 cents per plastic and paper bags.
In addition to grocery stores, restaurants and retail will also be enforcing the ban. Santa Monica is following suit after San Francisco, Malibu, and unincorporated parts of Los Angeles County have banned plastic bags. -AA
Information from KTLA.