Cal. Food & Agric. Code § 38881

Lactose reduced milk, reduced-fat lactose reduced milk, lactose reduced lowfat or light (lite) milk, and lactose reduced nonfat, skim, or fat-free milk are market milk products resulting from the treatment of milk, reduced-fat milk, lowfat or light (lite) milk, or nonfat, skim, or fat-free milk by the addition of safe and suitable enzymes to convert sufficient amounts of the lactose to glucose or galactose so that the remaining lactose is less than 30 percent of the lactose in milk, reduced-fat milk, lowfat or light (lite) milk, or nonfat, skim, or fat-free milk.