Filling in the Gaps

The Roman system of contracts left out of account many agreements that deserved enforcement, especially in a developed economy. The jurists clearly recognized the limits of their system, in particular the sometimes obscure boundaries of recognized contracts and the difficulty in recognizing new ones. For agreements that could not be accommodated, they eventually developed a rather awkward mechanism whereby, in principle, a contractual promise only became enforceable after one party performed its side, after which it could demand that the other party either carry out its promise or provide restitution of unjustified enrichment. This mechanism provides relief, but is obviously imperfect. Still, the jurists were at least willing to carry over from the recognized contracts some implied rights and duties.