A proposed Tennessee bill would give state judges discretion to allow therapy dogs into the courtrooms. Presumably, the dogs could comfort vulnerable witnesses such as children. A lot of research has demonstrated these benefits and the idea has been used for years in other jurisdictions.
There is an important distinction between these therapy dogs and service animals. The use of a service animal, such as a "seeing eye dog," is protected by the Americans with Disabilities Act, among other things. However, therapy or comfort animals are not offered the same protection
Some county courts already allow the use of therapy dogs, but the proposed bill would remove any concerns about the legality of the use. Judges are often nervous about novelty, when there will be a losing party looking for grounds to appeal.
One sticking point for the use of therapy animals is how does one know when it is a real therapy animal, and not just a pet. This article noted that one of the sticking points of the proposed bill was whether the therapy animal must have a record of its training. This is a trust issue. In the court context, it is unlikely for someone to claim that her pet is a therapy animal in order to get it into the courtroom. On the other hand, in the housing rental business, tenants may be tempted to call their pet a therapy animal in order to get around "no pet" provisions and policies.
Requiring registration, while sounding logical, has the effect of prohibiting many animals. Someone may have a dog that makes life much more manageable for her without going to the trouble of getting training or registration. It doesn't take always take any training for a dog to be able to comfort its owner. A child subpoenaed for a court hearing might not have the time or money to get a dog properly trained and registered.
In all likelihood, requiring anything more than nominal registration would have a chilling effect on the use of such animals.
For more information, you can check out the Courthouse Dogs Foundation.