If a written agreement is dependent upon some event before it becomes enforceable, then oral evidence may be offered concerning that condition precedent. A condition precedent is an act or promise that must take place or be fulfilled before the other party is obligated to perform his or her part of the agreement.
As a final exception to the parol evidence rule, some regulations allow oral testimony about how the parties have done business together over a long time period. These regulations make allowance for this type of testimony because, from a practical point of view, parties often get so used to dealing with each other in a particular way that they neglect to include certain terms in their written agreements. Similarly, some practices are so universal in a particular trade, business, or industry that the parties feel no need to include such universal practices in their written contracts. Accordingly, regulations allow oral testimony to supplement a written agreement as to these practices.
Under the best evidence rule, the courts generally accept into evidence only the original of a writing, not a copy.
Under this rule, a written instrument is regarded as the primary or best possible evidence. Thus, the best evidence rule concurs with and supports the parol evidence rule.
The equal dignities rule provides that when a party appoints an agent to negotiate an agreement that must be in writing, the appointment of the agent must also be in writing.
Certain formalities are usually followed in the formation of other than the simplest kinds of written agreements. While a law may necessitate nothing more than the briefest written disclosure of promises, conditions, and terms, plus the signature(s) of the obligated party or parties, usually contracts in general commercial and consumer use are carefully written, researched for legal compliance, and signed. Furthermore, leases and contracts for the sale of real property may have additional requirements of content and formality that extend beyond these formalities.
Written agreements should be, but need not be, signed by both parties. If signed by only one party, any obligation on the agreement would be limited to that party alone.
Witnesses are required in the signing of a will, but in most other documents their signatures are at the option of the contracting parties. To ensure that no misunderstanding will arise as to the acceptance and signing of a written agreement, the use of witnesses is advised. Certain official documents, such as a certificate of title to a motor vehicle, require the owner's signature and an acknowledgment by a notary public when transferring ownership. The notary witnesses the signing of the document and then acknowledges this act by signing the document and adding the official seal to it. A notary is not authorized to read the document being signed and may be prevented from doing so. The notary's legal authority includes the act of acknowledging another's signature to be the result of this person's own free act and deed before the notary.
