Proximate cause can be defined as an act from which an injury results as a natural, direct, uninterrupted consequence, and without which, the injury would not have occurred. It may not necessarily be the closest cause or the first event, which can make proving proximate cause a complex affair.
Courts use the “but for” rule in order to assess proximate cause and determine whether an injury would have occurred without the negligence of the defendant. Making the determination that the injury would not have occurred without the negligent factor then makes a particular act the “proximate cause” of the injury, although this alone does not establish liability.
Some jurisdictions choose to use what they call the “substantial factor” formula in order to determine proximate cause. This means the court considers whether the conduct of the defendant was a substantial factor in causing the damage; in this case the defendant will be held liable for resulting damages unless he or she can prove otherwise.
In order for a plaintiff to receive an award for damages because of negligence or another wrongful act, it is essential to determine fault and prove the negligent actions of the defendant were the proximate cause of damages to the plaintiff (and not some other action).