"A British court later rejected this argument as scientifically false, finding that 149 °F (65 °C) liquid could cause deep tissue damage in only two seconds."
"If this submission be right, McDonald's should not have served drinks at any temperature which would have caused a bad scalding injury. The evidence is that tea or coffee served at a temperature of 65 °C will cause a deep thickness burn if it is in contact with the skin for just two seconds. Thus, if McDonald’s were going to avoid the risk of injury by a deep thickness burn they would have had to have served tea and coffee at between 55 °C and 60 °C. But tea ought to be brewed with boiling water if it is to give its best flavour and coffee ought to be brewed at between 85 °C and 95 °C. Further, people generally like to allow a hot drink to cool to the temperature they prefer. Accordingly, I have no doubt that tea and coffee served at between 55 °C and 60 °C would not have been acceptable to McDonald's customers. Indeed, on the evidence, I find that the public want to be able to buy tea and coffee served hot, that is to say at a temperature of at least 65 °C, even though they know (as I think they must be taken to do for the purposes of answering issues (1) and (2)) that there is a risk of a scalding injury if the drink is spilled."
"A British court later rejected this argument as scientifically false, finding that 149 °F (65 °C) liquid could cause deep tissue damage in only two seconds."
https://en.wikipedia.org/wiki/Liebeck_v._McDonalds_Restauran...
"If this submission be right, McDonald's should not have served drinks at any temperature which would have caused a bad scalding injury. The evidence is that tea or coffee served at a temperature of 65 °C will cause a deep thickness burn if it is in contact with the skin for just two seconds. Thus, if McDonald’s were going to avoid the risk of injury by a deep thickness burn they would have had to have served tea and coffee at between 55 °C and 60 °C. But tea ought to be brewed with boiling water if it is to give its best flavour and coffee ought to be brewed at between 85 °C and 95 °C. Further, people generally like to allow a hot drink to cool to the temperature they prefer. Accordingly, I have no doubt that tea and coffee served at between 55 °C and 60 °C would not have been acceptable to McDonald's customers. Indeed, on the evidence, I find that the public want to be able to buy tea and coffee served hot, that is to say at a temperature of at least 65 °C, even though they know (as I think they must be taken to do for the purposes of answering issues (1) and (2)) that there is a risk of a scalding injury if the drink is spilled."
http://www.bailii.org/cgi-bin/markup.cgi?doc=/ew/cases/EWHC/...