i)
on the basis of a contract or obligation or gratuitous disposition which is void or retrospectively avoided pursuant to Principle IV.7.3, or
ii)
without legal capacity to make them, or
iii)
under an express or implied reservation of a right of recovery, or
iv)
for a purpose which is not realized or does not materialize.
2 Even if there is a legal basis for the enrichment under No. i) or ii), e.g. a contract, the enrichment is unjustified and must be restored under the basic rule in case where the party rendering the performance has made an express or implied reservation of a right of recovery or if that party's purpose which it has pursued with its performance has failed or its expectations connected with that performance have been disappointed (No. iv)).
Please cite as: "Commentary to Trans-Lex Principle , https://www.trans-lex.org/959100"