What are your reqirments for someone to purchase a puppy?

I'm not a breeder but rather a shelter volunteer. Our requirements for any animal is that the animal must have a sufficient living area, access to indoors in the harsh temperatures, all family members and household buts must demonstrate positive interaction prior to the animal leaving the facility, for dogs the yard must be fenced in with at least a 6 ft fence and no holes, they can not leave until they are spay or neutered, they must p a background check, and if they require special needs that are expensive we do a credit check. We also do at least two follow-up visits which the owners have to agree to. If anything violates the contract then we take the pet back and if need be press charges. Luckily we haven't had to do that as long as I've been there. I'm sorry to hear what happened to you but I'm glad you are taking steps to make sure it doesn't happen in the future. Good luck.