regarding the consequences of non-redemption of the pledge as part of their conventio pignoris. Thus, for instance, they could agree on a conditional transfer of ownership on the basis of either sale or datio in solutum. If the debt remained undischarged, the pledgee was to be taken to have bought the pledge or to have received and accepted it in lieu of fulfillment. Such clauses represent the contractual variant of the old forfeiture regime, and it is obvious that they are problematic and dangerous. If the pledge was valuable, the creditor would try to insist on their inclusion in the contract, and the debtor, hard pressed for money and overoptimistic as far as his ability to repay was concerned, was usually not in a position to resist these pressures. The Romen lawyers, therefore, tried in various ways to mitigate the effect of these forfeiture clauses, in order to protect the pledgor; in post-classical times, such clauses fell foul of Constantine' s prohibition of leges commissoriae and were regarded as invalid" .
R. Dannenbring Roman private law ( 3rd ed. ) (A translation
based on the tenth revised German edition of Romisches (Provatrecht by Max Kaser) comments in similar vein at 161:
"However, in consequence of the shortage of credit prevailing in the post-classical time misuses by usurious exploitation multiplied, in that creditors accepted things the value of which far exceeded the value of the secured debt, in order to make an excessive profit where the
debtor proved to be unable to pay. A statute of Constantine (A.D. 320), therefore, prohibited the clause which provided for the foreclosure ( lex commissoria, a lex contractus = term of a contract) and Justinian retained this regulation (CTh.3.2.1 = C.8.34.3)".
Voet 20.1.25 explains the reason for the prohibition in the following terms (Berwick's translation):
"Inasmuch as if it might be agreed upon that when a debt is not paid within a certain time the creditor is to retain (as his own) the thing pledged for the debt, things of the greatest importance and value would often be ceded in payment of a very trifling debt; the debtor, needy and pressed by the straitened condition of his pecuniary circumstances, readily submitting to the insertion of hard and inhuman conditions (in the bond) and holding out to himself the promise of better times and fortune before the arrival of the day fixed by the pactum commissorium, and hoping that the asperity of the pact will be averted from him by payment; a slippery and fallacious hope, however, to which the event not rarely fails to respond".
This passage (in Berwick's translation) is quoted with approval in Mapenduka v. Ashington, supra, at 351.
G. F. Lubbe, Mortgage and Pledge, in The Law of South Africa (ed. Joubert) Vol. 17 p. 285 at 327 states the following in dealing with the pactum commissorium in the case of mortgage and pledge:
"The ratio for the prohibition of this clause lies in the inherent possibility that a prospective credit grantor may exploit the weak financial position of a borrower and the latter's too often misplaced optimism about his prospects, in order to obtain, by way of a pactum commissorium a windfall disproportionate to the extent of the indebtedness towards himself".
While the prohibition against the pactum commissorium in the case of mortgage and pledge simpliciter is well established in the modern derivative Roman Dutch law systems (as appears from the authorities cited by my brother MAHOMED) the reason for such prohibition is equally well-established and clear as aptly summarised by Lubbe, supra.
Save for a passage cited to us from de Blecourt and Fischer Kort Berip van Het Oud-Vaderlands Burgerlijk Recht at 258 (par. 182) we were referred to no authority which expressly-sought to apply the prohibition against a pactum commissorium to the case of a cancellation clause in a deed of sale where the res vendita is to be burdened (and subsequently is burdened) with a mortgage bond as security for payment of the purchase price.
As my bother MAHOMED has pointed out, the Courts will ordinarily enforce the provisions of an agreement in terms of which a seller is given the right to cancel an agreement for the sale of property, if the purchase price is not paid and a claim for the restitution of the res vendita following upon such cancellation enforced. It is interesting to note that in Baines Motors v. Piek 1955(1) SA 534(A) at 542 H, van den Heever, J.A., dealing with the enforceability of a lex commissoria in a contract of sale, remarked as follows:
"The lex commissoria annexed to a contract of pledge, which has also been mentioned in this connection, has no bearing upon our problem. It was a condition that, if the debtor fails to pay on due date, the pledged article becomes the property of the pledgee. By decree the Emperor Constantine declared such pacts invalid with retrospective effect on the ground of their being oppressive..." (emphasis added)
and observed at 543 H- 544 A that
"It appears, therefore, that the same agency which has in general abolished the Roman-dutch rules governing