Cal. Pub. Res. Code § 42281.2

(a) On and after January 1, 2025, a store, as defined in Section 42280, shall not provide a precheckout bag to a customer if the bag is not one of the following:
1. (1) A compostable bag that meets all of the following criteria:
  1. (A) Complies with the standards described in Section 42357.5.
  2. (B) Is eligible to be labeled with the terms “compostable” or “home compostable” pursuant to Section 42357.
  3. (C) Has a minimum 15-inch mouth width.
2. (2) A recycled paper bag.
(b) For purposes of this section, a “precheckout bag” means a bag provided to a customer before the customer reaches the point of sale, that is designed to protect a purchased item from damaging or contaminating other purchased items in a checkout bag, or to contain an unwrapped food item, such as, but not limited to, loose produce, meat or fish, nuts, grains, candy, and bakery goods. “Precheckout bag” does not include a bag used to prepackage items prior to their arrival in a store.