Coffee and tea are usually made with boiling or close-to-boiling water. Water in an open container at sea level simply can't get much hotter than 'boiling'. The argument that the coffee was 'too hot' seems specious. Instead, the design of the cup is the more important issue - the company was serving hot coffee in a cup that was prone to failure.

I don't understand your comment. We don't clean cups with cyanide. What point are you trying to make?

Nor do we have a law against hot coffee. But if you do something negligent or with foreseeable harm then you may be liable, as McDonald's was, in a tort.