[F]our elements . . . must coalesce to impose liability for intentional infliction of emotional distress:
- The conduct must be intentional or reckless;
- The conduct must be extreme and outrageous;
- There must be a causal connection between the wrongful conduct and the emotional distress;
- The emotional distress must be severe.
For a defendant to be liable for injury to a close relative of the plaintiff's, the plaintiff must have been present and a close relative, and the defendant must have known that the plaintiff was present and a close relative.
The Restatement 2nd of Torts gives an alternative where the plaintiff also received harm.
If the vulnerability is apparent or known to the defendant, the plaintiff's particular vulnerability will be taken into consideration.
Sometimes IIED is called "outrage".