California has officially passed a law banning pet shops from selling pets unless they have worked with a shelter or rescue group to provide the animals.
Assembly Bill 485 was signed into law on Friday (local time), the Orange County Register reported. It means that from January 2019 pet stores that do not sell rescue animals will face a $500 fine.
More than 230 cities, towns and counties across the US have similar laws, but California is the first to make the law statewide.
The law has two main goals. The first is to reduce the number of dogs bred in so-called "puppy mills" and other animals which are bred in large volumes in horrific conditions.
Lawmakers also hope that the change will promote the adoption of homeless pets. The American Society for the Prevention of Cruelty to Animals estimates that 1.5 million companion animals were euthanized in shelters across the US in 2016.
The ASPCA are vocal supporters of the law, saying that it will encourage breeders away from the use of puppy or animal mills.
In a statement to the Huffington Post, Matt Bershadker, CEO and President of the ASPCA, praised the law for breaking "the puppy mill supply chain that pushes puppies into California pet stores and has allowed unscrupulous breeders to profit from abusive practices."
Not everyone is in favour of the new law though, with breeders criticising the law for reducing the choice for prospective pet owners and preventing owners from having access to ethical breeders.
The law does not prevent owners from purchasing animals from breeders, but they cannot be sold via pet stores and breeders will have to sell to owners directly.