I disagree with the idea of an ESA and generally try to avoid getting involved with that stuff.
I am actually somewhat open to the idea that people with certain types of mental illness might benefit from having a service animal, and I might consider recommending a patient for a service animal in the right circumstances. If I’m honest, I’m not sure if there is a literature base for such things, but I could imagine a service animal helping an otherwise fairly functional psychotic person maintain reality testing, or something similar.
The core of the problem with the ESA thing, for me, is that they are not service animals. Service animals are selected based on temperament and receive specific training. The process of qualifying one also seems more rigorous. Because of that, I think there is a good case as to why service animals should be exempt from rules about where animals can and can’t be. For instance, a movie theater might not want dogs for some obvious reasons, but a service dog is almost certainly not going to interrupt the movie by barking for no reason. That is not an expectation you can just have of animals generally.
I will also admit that I am not fully literate on the process of obtaining a service animal. It may be that it is practically almost impossible to get one for a mental health diagnosis. If that’s the case, I would support expanding the access to them and training animals to specifically deal with mental illness (to the extent that is feasible). Fundamentally, though, I think that the service animal model is the one to follow if we’re going to be exempting patients from the usual prohibitions on animals.
I think that it is undeniable that many patients would benefit from having an animal. Some might even benefit from having an animal with them most of the time. That said, other stakeholders also have interests in generally prohibiting animals from certain places. Businesses might not want the disruption of animals, workplaces might not want the distraction an animal brings, apartments might not want the risk that a poorly behaved animal will damage things, etc. I think that clear standards for temperament, behavior, and handling (I.e. when the service animal is working, such as when the owner is at work, nobody is allowed to pet or play with the animal, thereby minimizing distraction), serve a critical role in balancing the benefit of animals for certain populations and the concerns of the other stakeholders.