Here are some examples of treaties that can only be implemented in writing: According to the Houston Chronicle, an oral contract is not an oral agreement and not a written agreement. Many types of oral contracts are legal and may be applicable in California and other countries. However, it is often difficult to enforce an agreement based solely on words. Despite the fact that the written instruction of all contracts remains a better and safer practice, many important trade and partnership agreements are still concluded orally. While oral contracts are enforceable in California in many circumstances, the California Civil Code expressly requires that certain agreements be in writing in order to be enforceable. Oral agreements are subject to other important restrictions, depending on the nature of the transaction and the amount of money. . . .