"What could the owner have done to ensure that this did not happen? For all we know he tried the swing himself the day before and it was fine. At least at the time of making the advert it was still fine and short of 'destructive testing' to figure out how much load it supports there is no way to know what it will handle except for trying to see if it supports your weight."
This falls into the area of "jury argument" ;-)
However, i will point out "if you can't figure out whether it's safe, you generally have a duty to remove it or warn people it's possibly not safe".
(Whether i like the law or thing it just generates tons of warning labels, that is the law).
If I try the swing today and it is safe (with my weight, and with my use of the swing) trying my hardest to see if it will break and it does not, then the next day you come by and you sit on it and it breaks am I liable?
Should I have judged my test as 'inability to figure out if it was safe'?
Nothing short of a destructive test will tell you exactly what load a swing like this will support, but common sense will tell you to be careful with tree swings regardless of whether or not someone tells you that it is safe. It's a non-engineered project probably made on a budget (even though in this particular case the tree swing had chains rather than rope so it was constructed fairly well) and it ended up being the tree trunk that snapped rather than the branch the chains were attached to.
This falls into the area of "jury argument" ;-)
However, i will point out "if you can't figure out whether it's safe, you generally have a duty to remove it or warn people it's possibly not safe".
(Whether i like the law or thing it just generates tons of warning labels, that is the law).