[PAULUS libro tertio quaestionum. ] §12.6.60.prIulianus uerum debitorem post litem contestatam manente adhuc iudicio negabat soluentem repetere posse, quia nec absolutus nec condemnatus repetere posset: licet enim absolutus sit, natura tamen debitor permanet: similemque esse ei dicit, qui ita promisit, siue nauis ex Asia uenerit siue non uenerit, quia ex una causa alterius solutionis origo proficiscitur.
[PAULUS, in the third book of Questions.] Julian denied that a true debtor, after joinder of issue (litis contestatio) and while the trial is still pending, could recover what he has paid, because neither one who has been acquitted nor one who has been condemned can recover; for even though he is acquitted, he nevertheless remains a debtor in natural law. And he says that such a debtor is similar to one who has promised thus: "whether a ship comes from Asia or does not come," because from a single cause arises the origin of one or the other payment.
§12.6.60.1Ubi autem quis quod pure debet sub condicione nouandi animo promisit, plerique putant pendente nouatione solutum repetere posse, quia ex qua obligatione soluat, adhuc incertum sit: idemque esse etiam, si diuersas personas ponas eandem pecuniam pure et sub condicione nouandi animo promisisse.
But where anyone has promised under a condition, with the intention of creating a novation (animus novandi), what he owes unconditionally, most jurists think that he can recover what he paid while the novation is pending, because it is still uncertain under which obligation he is paying. The same is held even if you assume that different persons have promised the same money, one unconditionally and the other under a condition with the intention of creating a novation.
sed hoc dissimile est: in stipulatione enim pura et condicionali eundem debiturum certum est.
But this is different; for in an unconditional and a conditional stipulation, it is certain that the same person will be the debtor.