If the owner of the swing wants to use the swing then he too has the responsibility of making sure it is safe for his&#x2F;her use.<p>For all we know the owner of the swing tried it the day before but weighed 10 kg less than the guest and he&#x2F;she never noticed a problem. For every tree-swing there is a point in its life where it will fail and a load that will cause it to fail <i>right now</i>.