What is Restitutio Ad Integrum?

Legal Definition
Restitutio ad integrum is a Latin term which means restoration to original condition. It is one of the primary guiding principles behind the awarding of damages in common law negligence claims. The general rule, as the principle implies, is that the amount of compensation awarded should put the successful plaintiff in the position he or she would have been had the tortious action not been committed. Thus the plaintiff should clearly be awarded damages for direct expenses such as medical bills and property repairs and the loss of future earnings attributable to the injury (which often involves difficult speculation about the future career and promotion prospects).

Although monetary compensation cannot be directly equated with physical deprivation it is generally accepted that compensation should also be awarded for loss of amenities, reflecting the decrease in expected standard of living due to any injury suffered and pain and suffering. Damages awards in these categories are justified by the restitutio principle as monetary compensation provides the most practicable way of redressing the deprivation caused by physical injury.
-- Wikipedia