the classic english legal case is donahue vs stevenson or m'alistar v stevenson and it was not an english case it was a scottish case that went to the british house of lords judicial committee for final appeal . as such it became english as well as scottish law. the case introduced the scottish principle called the neighbourhood principle into english law. this principle, which comes from old gaelic brehon law, states we owe a duty of care for our neighbours based on the standard of what a reasonable peron would think the duty should be. this begins negligence law in english common law. prior to that english law had only intentional torts. after this case you get negligent torts and all the amblunance chasers that come after that.
so here's to ancient brehon law in the modern world