@S1969, No, I am definitely not a lawyer, but neither am I just guessing. I have owned, managed, and rented farms and equine businesses for decades and have consulted with insurance agents and lawyers many times regarding these exact issues. I strongly recommend that anyone with specific real life questions should consult their insurance agent–it’s an easy phone call–and consider involving a lawyer in your state for recommendations.
Anyway, a commercial policy protects a BO from liability related to any negligence on the part of the BO/the business/ the employees. The fact that an accident occurred on the premises does not necessarily = negligence on the part of the barn. Let’s take the case you describe, where a self-care boarder makes an agreement with another boarder to take turns feeding and turning out the horses, and one of the boarders gets kicked in the head. I think it would likely be a challenge to go to court and prove that the BO was somehow negligent in that scenario. Obviously it also might be difficult to surmount any state statutes limiting equine liability and/or any liability releases that may have been signed.
I agree with you 100% that lawsuits can always happen and a BO should be appropriately insured, because defending a lawsuit with little-no merit can still be expensive.
I’m sorry that you are in that situation WRT your current lawsuit. I don’t think that there are a lot of parallels between automobile insurance/liability and equine commercial insurance/liability, but that still seems like a very difficult and stressful situation.