The Concept of Non-Contractual Obligations

a) Void contracts 
Nevertheless, this approach may lead to serious problems. This can be clearly seen 
in cases where the reversal of the void contract is obstructed because one party finds 
itself unable to restore what it has received under the contract, be it because of the 
nature of the benefit or because it has been damaged or destroyed. A classical 
example is a – void or voidable – contract for sale. If a car which was transferred on 
the basis of a void contract is destroyed, perhaps even by the buyer‟s fault, the law 
must decide whether the buyer may still claim back the purchase price. From an 
unjustified enrichment perspective, it is difficult to explain why that should not be 
the case. Is it not obvious that the payment was made without legal ground? It 
follows, apparently, that the buyer is entitled to claim back his money without 
paying compensation for the destroyed object of sale. However, this is so manifestly 
unjust that European courts have only exceptionally
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accepted such a result.
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A closer view reveals that this problem basically results from the fact that 
non-contractual remedies take an abstract and one-sided perspective on the reversal 
of contracts. Within the doctrinal framework of unjustified enrichment it does not 
matter whether the claimant has performed under a void contract or for any other 
reason. The unjustified enrichment approach thus isolates the mutual claims from 
each other. Yet parties to a contract perform upon consideration of the stipulated 
counter-performance.
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From a normative point of view, this is a highly important 
factor that must be taken into account when unwinding a contract.
For this reason, European courts have usually re-connected the isolated 
claims for the contract partner‟s unjustified enrichment into a 
contrat 
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Apparently, this is the case under Italian law. Here, the prevailing opinion does not see any 
possibility of overcoming the Codice civile‟s approach of treating the 
condictiones
independently of 
each other. Thus, whereas the seller will always be obliged to pay back the full price received under 
the contract, the buyer will only have to give back what is left. Yet voices who want to construct a 
„reversal-contract‟ in order to avoid this result are increasingly heard (see 
A di Majo
, Restituzioni e 
responsabilità nelle obbligazioni e nei contratti [1994] Rivista Critica del Diritto Privato 291, 323 f); 
and the courts have also occasionally found ways to avoid unsatisfactory results; see 
Schlechtriem
(fn 3) vol I, 467 f, with further references. Likewise, although the prevailing opinion in Poland 
proceeds from the assumption that the claimant‟s and defendant‟s 
condictiones
are legally 
independent of each other, the courts have only exceptionally granted a 
condictio
to a party that was 
not prepared to give back at least the value of the benefit received: see 
Schlechtriem
(fn 3) vol I, 
543 f, with further references. 
55
Schlechtriem 
(fn 3) vol I, 403–753; see also 
W Lorenz
, Inhalt und Umfang der Herausgabepflicht 
bei der Leistungskondiktion in rechtsvergleichender Sicht, in: Ungerechtfertigte Bereicherung. 
Grundlagen, Tendenzen, Perspektiven. Symposium zum Gedenken an Detlef König (1984) 127–149, 
140 ff. 
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A Bolze
, Der Anspruch auf Rückgabe aus einem nichtigen Geschäft (1890) 76 Archiv für die 
civilistische Praxis (AcP) 233–264, 238 ff, 241 f, in recourse on French literature and judgments. 

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11 
synallagmatique renversé
.
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Indeed, the principle of restitution being reciprocal 
(