ycbm
Overwhelmed
Because from what i understand the YO hasn't provided a safe environment for the horses to come in/out of the gate.
But everyone who is a livery there can clearly see that and has accepted both the gate situation and the practice of feeding horses just outside the gate. The YO would possibly be liable if a horse got out on the road but I can't see how they are liable for grown adults who choose to keep their horses at that yard. The setup is completely normal. There are many better but it's far from uncommon to have only one gate.
If you choose to keep your horse at a place like that, why should you expect to be able to sue the owner if it goes wrong?
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