In a lawsuit, if the plaintiff successfully proves that the defendant's negligence was the actual cause of injury, the plaintiff must also show that the defendant proximately caused the damage. This is called the proximate cause and is also referred to as the legal cause.

What does the issue of proximate cause boil down to? Why do courts struggle with this concept?

Reference:

David C. Owen, The Five Elements of Negligence, 35 HOFSTRA L. REV. 1672 (2007).