Federal law makes it a crime to deny access for service animals.
But, federal law does allow managers to question the specific purpose that the dog is serving.
We’re all aware of that...the question is, should it? And from where in the constitution does the federal government derive said authority? We should ask that about every federal law.
The federal government is too big and is regulating things that are better left to smaller entities, such as state and local governments, or families, or individuals. Subsidiarity is an important, and largely forgotten, rule of governance.