There is NO Federal Law which regulates the care of pet animals by private owners or animal shelters. However, every state in the US has animal cruelty statutes which prohibit cruel treatment and/or require an owner to provide proper shelter, adequate nutrition and clean water, a sanitary safe environment, and necessary veterinary care. Thus, on a very simple level, it seems that hoarding would be an obvious violation of the most basic provisions. To review the applicable Animal Cruelty Laws in your state, click on the link (be sure to check the box LAWS in the upper left box and choose Abuse/Cruelty under category).

In actual practice, establishing a violation of the law is more difficult than it might appear from reading the statutes, for a variety of reasons. First, the language in the legislation is often vague and antiquated, leaving ample room for interpretation. Here is representative text, taken from the Massachusetts Code:

CHAPTER 272. CRIMES AGAINST CHASTITY, MORALITY, DECENCY AND GOOD ORDER Section 77 Cruelty to animals:

Whoever .... having the charge or custody of an animal, either as owner or otherwise, inflicts unnecessary cruelty upon it, or unnecessarily fails to provide it with proper food, drink, shelter, sanitary environment, or protection from the weather, and whoever, as owner, possessor, or person having the charge or custody of an animal,.... or knowingly and willfully authorizes or permits it to be subjected to unnecessary torture, suffering or cruelty of any kind shall be punished by a fine of not more than one thousand dollars or by imprisonment for not more than one year, or both.

Unfortunately, when these cases reach the courts, words such as "unnessary","proper", "knowingly" and "willfully" can be fatal in cases in which intent is unlikely and difficult to prove regardless, when proper standards of care are not defined in statute, and when extenuating personal circumstances of the hoarder can provide a loophole for defining what is "necessary". An additional problem is that much of the cruelty which arises in these situations is psychological suffering from chronic neglect, intensive confinement in small cages, and lack of opportunities to socialize with either people or other animals, or being confined in close proximity to animals which may be aggressive or threatening. These are factors which might best be described as "Quality of Life" issues, something which is almost uniformly absent from existing statutes in any explicit sense. Therefore, each court is left to its own combination of expert testimony and prevailing community standards.

Even when statutory husbandry standards exist, often they apply only to specific entities such as pet stores, shelters, kennels, and catteries. One of the most comprehensive state statues which avoids many of these definitional loopholes is the Colorado Pet Facilities Act.

Despite these obstacles, investigation under the cruelty to animals statutes is often the only way to begin an intervention in hoarding cases. Such an investigation should be conducted by, or with guidance from, a highly experienced humane investigator. From start to finish, the collection of evidence in these cases needs to be airtight to get a search warrant that will stand up and lead to either a conviction or the possiblity of a favorable negotiated agreement or plea bargain.

Illinois is the first state in the US to define animal hoarding in its state cruelty statute

Similar (but NOT identical) legisltation has been submitted, but not passed, in Vermont and New Mexico.