This entry contains information applicable to United States law only. A mark or sign made by an individual on an instrument or document to signify knowledge, approval, acceptance, or obligation.
The term signature is generally understood to mean the signing of a written document with one's own hand. However, it is not critical that a signature actually be written by hand for it to be legally valid. It may, for example, be typewritten, engraved, or stamped. A signature consists of the act of writing one's name, coupled with the intention of authenticating the instrument or document signed. The purpose of a signature is to authenticate a writing, or provide notice of its source, and to bind the individual signing the writing by the provisions contained in the document.
Because a signature can obligate a party to terms of a contract or verify that the person intended to make a last will and testament, the law has developed rules that govern what constitutes a legally valid signature. The Internet and other forms of telecommunication have created the desire to transact legally binding agreements electronically. Some states are beginning to pass laws that recognize the validity of "digital signatures."
Requisites and Validity
When an instrument must be signed, it is ordinarily adequate if the signature is made in any commonly used manner. Variations between the signature and the name appearing in the body of the instrument do not automatically invalidate the instrument.
In the absence of a statutory prohibition, an individual can use any character, symbol, figure, or designation he wishes to adopt as a signature, and if he uses it as a substitute for his name, he is bound by it. For example, if a contract refers to "William Jones" but Jones signs his name "Bill Jones," the contract is still enforceable against him. An individual can also use a fictitious name or the name of a business firm. A signature might also be adequate to validate an instrument even if it is virtually illegible. The entire name does not have to be written, and the inclusion of a middle name is not significant.
An individual satisfies the signing requirement when someone who has been duly authorized to sign for him does so. In the event a statute mandates an instrument be signed in person, the signature must be made in the signer's own hand or at his request and in his presence by another individual.
In a situation where an individual intends to sign as a witness but instead inadvertently signs the instrument in the place where the principal is to sign, the fact that she should have signed as a witness can be shown. Conversely when a signer intends to sign as a principal but instead signs in the place for a witness, that fact can also be shown.
Abbreviations, Initials, or Mark
In situations that do not require a more complete signature, an instrument can be properly signed when the initial letter or letters of the given name or names are used together with the surname (J. Doe), when only the full surname is used (Doe), when only the given name is used (John), or even when only the initials are used (J. D.).
A mark is ordinarily a cross or X made in substitution for the signature of an individual who is unable to write. In the absence of contrary statutory provision, a mark can be used by an individual who knows how to write but is unable to do so because of a physical illness or disability. A mark has the same binding effect upon the individual making it as does a signature. In some statutes a signature is defined as including a mark made by an individual who is infirm or illiterate.
Generally the name of the person who makes her mark can be written by anyone, and the mark is not necessarily invalidated because the individual writing the name accompanying the mark misspells the name or because the words stating that the symbol is intended as a mark are omitted. In the absence of a statute that requires a name to accompany the mark, the validity of the mark as a signature is not affected by the fact that a name does not accompany it.
When a mark is used as a signature, it can be put wherever the signature can appear. When there is a requirement that the name must accompany the mark, the fact that the mark and the name are not in immediate proximity does not invalidate the mark.
Certain statutes mandate that a witness must attest to a signature made by a mark. Under such statutes, if the mark is not properly witnessed, the instrument is not signed and is legally ineffective. These laws were enacted to prevent fraud, because it is difficult, if not impossible, to later determine if the alleged signer actually made the mark.
Hand of Party or Another
A signature can be written by the hand of the purported signer, either through the signer's unaided efforts or with the aid of another individual who guides the signer's pen or pencil. In cases when the maker's hand is guided or steadied, the signature is the maker's act, not the act of the assisting individual.
A signature can generally be made by one individual for another in her presence and at her direction, or with her assent, unless prohibited by statute. A signature that is made in this manner is valid, and the individual writing the name is regarded merely as an instrument through which the party whose signature is written exercises personal discretion and acts for herself.
Method
Ordinarily a signature can be affixed in a number of different ways. It can be hand written, printed, stamped, typewritten, engraved, or photographed. This allows, for example, a business to issue its payroll checks with the signature of its financial officer stamped rather than handwritten.
Digital Signatures
The computer and telecommunications have changed how work is done and how it is exchanged. Both business and the legal system have begun to explore ways of using the Internet and other forms of electronic communication to transact work. Court systems cannot permit the electronic filing of legal documents, however, unless the documents have been authenticated as coming from the sender. Similarly, businesses will not enter into contracts using the Internet or electronic mail unless they can authenticate that the other contracting party actually made the agreement. Computers and digital scanners can reproduce handwritten signatures, but they are susceptible to forgery.
A proposed solution is the legal recognition of "digital signatures." By 1997 five states had enacted laws that recognize the validity of digital signatures and thus bind parties to agreements or documents signed electronically.
A digital signature is based on cryptography, which uses mathematical formulas, or algorithms, to scramble messages. Using encryption and decryption software, the sender can scramble the message and the recipient can unscramble it. To affix a digital signature to an electronic document, a signer must obtain electronic "keys." The keys are assigned in pairs: a private key and a public key.
A person creates his keys using a software program. The digital signature is affixed to the electronic document using the private key. The "signer" types in a password, similar to a personal identification number for an automatic teller machine. The private key then generates a long string of numbers and letters that represent the digital signature, or public key. The recipient of the message runs a software program using this public key to authenticate that the document was signed by the private key and that the document has not been altered during transmission.
It is mathematically infeasible for a person to derive another person's private key. The only way to compromise a digital signature is to give another person access to the signature software and the password to the private key.
See: authentication.
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