It is a protected right by law under the Fair Housing Act and backed up by the Department of Housing and Urban Development.

As long as a person who is diagnosed with a disability (which includes autism under the ADA) provides evidence of their non-apparent disability in the form of an emotional support letter by a qualified and reputable party which can vouch for the presence of that person's disability, then a US landlord cannot deny that person their assistance animal, nor may they charge them a pet deposit or pet rent. They may only deny the request under certain conditions, outlined below.

"An assistance animal is an animal that works, provides assistance, or performs tasks for the benefit of a person with a disability, or that provides emotional support that alleviates one or more identified effects of a person’s disability. An assistance animal is not a pet

"Individuals with a disability may request to keep an assistance animal as a reasonable accommodation to a housing provider’s pet restrictions.

"The Fair Housing Act requires a housing provider to allow a reasonable accommodation involving an assistance animal in situations that meet all the following conditions:

• A request was made to the housing provider by or for a person with a disability
• The request was supported by reliable disability-related information, if the disability and the disability-related need for the animal were not apparent and the housing provider requested such information, and
• The housing provider has not demonstrated that:
• • Granting the request would impose an undue financial and administrative burden on the housing provider
• • The request would fundamentally alter the essential nature of the housing provider’s operations
• • The specific assistance animal in question would pose a direct threat to the health or safety of others despite any other reasonable accommodations that could eliminate or reduce the threat
• • The request would result in significant physical damage to the property of others despite any other reasonable accommodations that could eliminate or reduce the physical damage.

"A reasonable accommodation request for an assistance animal may include, for example:

• A request to live with an assistance animal at a property where a housing provider has a no-pets policy or
• A request to waive a pet deposit, fee, or other rule as to an assistance animal.