Restitution is a branch of private law.

But which branch is that? The major domains of private law are well settled. There is the law on ownership ("property law"), on which agreements are enforceable ("the law of contract"), and on what counts as wrongdoing which deserves compensation ("tort law" / "law of delict"). But it seems that in addition to those areas there is something else - Which we call (lacking a better word) "restitution".

What should we make of "restitution"? It has met with many reactions. It covers many diverse cases. Do these cases have anything in common?

A persistent thought, over perhaps 25 centuries of legal thought, has been that there must be something which binds these many instances together. So many writers support a theory of "unjust enrichment", which is supposed to unite the various instances of restitution and give them purpose. But others oppose this concept as an illusion, a hopeless hankering after harmony where there is only a messy miscellany. Who is right? Or is there some middle position, and if so, what? And should we be ashamed of restitution, as awkward rubbish which we should sweep under the carpet of the law? Or does the subject, on the contrary, have a rôle to make good the deficiencies of other domains of the law, correcting the injustices which the mechanical rules of other areas sometimes unwittingly do?

More pragmatically, while academic and judicial argument is unceasing, it is pretty clear at least what the subject-matter is. In simpler words: We see no end to the argument, but at least we know what we are arguing about. So "the law of restitution" certainly includes the law relating to mistake, unfair pressure, tracing of stolen property, and recovery of the proceeds of wrongdoing. It also covers more esoteric but nonetheless important legal institutions: salvage, contribution, subrogation, constructive trust. (And if you don't know what those words mean, then you are in the majority of the human race - Nonetheless, ownership of millions of £$¥ per day depend on the precise application of those concepts.) It covers much more besides, though there is plenty of disagreement as we reach the fringes.

Restitution, then, is an important legal topic, and these pages are an attempt to convey information about the issues. Suggestions for improvement are very welcome!