Way back when – when I owned/managed my TBred training farm – my commercial liability policy covered ‘injury’ etc. to all who came onto the farm – invited or not. This type of policy covered everything unless ‘negligence’ could be proved.
So… besides the ‘Enter at Your Own Risk’ & ‘Horses are Dangerous’ signs (for all the good those would do) I always placed an orange traffic cone in the aisle in front of the biter/lunger stalls to remind everyone to give those horses a wide berth. As in all racing barns (especially at the racetrack) horses are never locked in behind bars/closed doors. Thus traffic cones (or some other reminder) dot the aisles where needed…
…or yoked stall screens are used instead of webbings – placed extra high so horse could still look out but couldn’t lunge and grab someone. The screens limited the horse’s reach.
But since negilence is sometimes subjective, a court battle could occurr even with a liabilty policy…and as lep said, this is where equine immunity statutes become important.