It is not true that the Limitation Act purports to deal with all private law claims. Many equitable claims are, for example, not included. Whether the omission of any specific provision dealing with unjustified enrichment was deliberate is probably incapable of being given an answer. I have not checked Hansard.

In the example we were discussing, the obligation accrues at the same instant whether you look at the matter in 'breach of contract' terms or 'unjust enrichment terms'.

I agree that in the example it makes no difference. I was merely trying to balance the impression given that it will never make any difference.

Time for claims based upon a breach of contract will generally start from breach. Time for claims based upon unjustified enrichment will generally, but not always, run from the time of enrichment.

This begs an important question, by smuggling in the assumption that there is a coherent 'law of limitation for unjust enrichment claims'.

I did start by saying I was assuming that there was a coherent body of law concerned with unjustified enrichment. Whether or not I agree with that assumption is a different matter. It is clearly true that not all claims which might be classified as based upon unjustified enrichment are, for the purposes of limitation treated in the same way. That is why I said 'generally.'

Claims based upon the commission of a tort also generally carry a time limit of six years. Where a claim for breach of contract and the commission of a tort exist concurrently the different points at which time may begin to run can provide an incentive for the pleading of the claim in tort rather than in contract (Henderson v Merrett). The same may be true where a claim based upon unjustified enrichment exists concurrently with a claim for breach of contract.

That would be so if the contract/restitution line could be drawn in the same way as the contract/tort line. But for a number of reasons, which will be apparent on reading any good text on the history of private law, the lines are of a very different character, and the separation of contract from restitution incomplete at best.

I don't think those who would argue for a coherent body of law concerned with 'unjustified enrichment' would base this view on its historical provenance in English private law. Those who believe in this category include within it areas traditionally seen as distinct (e.g. the action for money had and received and some constructive trusts.) My view is that unjustified enrichment's sole justification for separate existence is that it is conceptually distinct. I would agree that 'torts' is a different type of classification from 'unjustified enrichment.' As you say in your recent textbook on tort, the exclusion from 'torts' of certain equitable wrongs appears to be historical accident. The historical classification of 'torts' is not entirely conceptually coherent therefore.

Robert Stevens