French, German and Common Law Contract Law are different in some points, but are also quite similar, at least in the solution, if not in the reasoning, of some juridical problems. In addition to the introduction of the French, German and English notions of contract law by Hugh Beale, I would like to focus on one basic difference between French and Common Law on the one hand and German law on the other hand. Furthermore I would like to highlight one practical similar but not identical solution of a juridical problem according to the three systems.
Lawyers in the three juridical systems use different terms for "contract". But in spite of different vocabulary and specifical conditions for the existence of a valid contract, the terms are comparable in the essential characteristics of a contract, the minimum common content would be an agreement about the essentalia negotii between two parties willing to create a legally binding relationship. Instead of a comparison of every single condition for a contract according to each system, I would like to underline a fundamentally different approach to the determination whether or not a valid contract exists by German lawyers in contrast to French and English lawyers. Contrary to the other legal systems, the system of the BGB uses the Willenserklärung as principal element. The reasoning about the formation of a valid contract is based on the determination of the validity of the Willenserklärung. The Willenserklärung is the decisive block. The logical construction of the contractual structure is based on a smaller unit than in the system of the Code civil or the Common Law. In the latter systems the contract might also be invalid for reasons related to a default of the expression of the will like dol, erreur or misrepresentation. But the departure point is a different one, it is the contract as a whole that is contested and not the single Willenserklärung. In German law it is the Anfechtung of the Willenserklärung for different reasons previewed by the BGB that may only consequently logically lead to the invalidity of the whole contract.
By reading the case Eccles v Bryant  about the question of the importance of the exchange of signed engrossment, it appeared to me that there are similar solutions for the legal subject of the sale of land. It is the solution that is comparable in the presence of three different methods. To reach certainty about the sale of land that is evaluated as important by all three legal systems, the Common Law insists on the exchange of the written and signed exemples of the contract as in the above mentioned case. The Code civil contains the rule about the lésion suitable to determine the invalidity of a contrat de vente d`immeuble in the case of an inadequate price. And the German system puts the validity of the sale of land under the regime of a notary.