A more thorough explanation:

An instrument is a written legal document that records legally enforceable acts or agreements and secures their associated legal rights, obligations, and duties. It can be used as evidence to prove the existence of such acts or agreements.

Examples of legal instruments include:

• Contracts
• Wills
• Promissory notes
• Deeds
• Statutes passed by competent legislatures

Legal instruments must be read as a whole, with every part interpreted in accordance with the whole. They are considered executed once they have been given validity and legal effect. For example, signing a contract executes the contract.

Most states allow non-lawyers to write their own instruments such as wills and contracts, but do not allow non-lawyers to charge third parties to draft complex legal instruments on their behalf that secure legal rights.

Historically, instruments were not considered properly executed until they had been sealed with wax or stamped. This requirement simplified authentication and enforcement, but today it has been done away with in most American jurisdictions to allow for greater ease in contracting.

However, a person who falsifies or materially alters a legal instrument with the intent to defraud another is guilty of the crime of forgery.

For example, a contract between two parties is an instrument that records the legally enforceable agreement between them. The contract can be used as evidence in court if one party breaches the agreement and the other party seeks legal action.