Any kind of burn is actionable if it is caused by negligence or a defective product. The degree of burn is a very important factor in determining the extent of one’s damages.
There are instances in which a burn might not fit the criteria for pursuing legal remedy. For instance, if a camp counselor who doesn’t apply sunblock to your small child, and the child receives a first degree sunburn, one could argue that the parent is responsible for applying sunblock to his or her young child before attending camp. So, that is not a case that I feel would be worthy of taking to court. Furthermore, a first degree burn is not likely to result in any provable long-term injury.
To determine whether a case is actionable, there are moral, legal and practical choices to be made, and one must weigh the severity of the burn, the circumstances and its cause to determine if there is any legal liability.