A new California law will go into effect this week banning pet stores from selling dogs, cats and rabbits from mass-breeding operations.

The Pet Rescue and Adoption Act, signed in 2017 by Gov. Jerry Brown (D), is intended to crack down on “puppy mills” and “kitten factories.” Starting Jan. 1, pet stores will only be allowed to sell animals from shelters or rescue groups.

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Pet store owners will now face a $500 penalty per animal if they do not provide records of origin, according to CNN. Californians can still purchase animals from private breeders.

State assembly member Patrick O’Donnell called the law, which is the first of its kind in the nation, a “big win for our four-legged friends,” according to CNN. O’Donnell introduced the bill.

The law was opposed by the American Kennel Club, who said that it would increase the chances of people buying pets that are not a good match.

The United Kingdom earlier this month banned third-party sales of puppies and kittens.