Legal Definitions - four corners of an instrument

The legal principle known as "four corners of an instrument" refers to the idea that when interpreting a written document, such as a contract, will, or deed, its meaning should be determined exclusively from the language contained within the document itself. This principle instructs courts and other interpreters to rely solely on what is written on the "pages" of the document, without considering information or evidence from outside the document (often called "extrinsic evidence").

This means that factors like verbal agreements made before the document was signed, the personal history of the parties involved, or the general circumstances surrounding the document's creation are typically not considered when trying to understand its meaning, unless the document itself contains unclear or ambiguous language. The core purpose is to uphold the written word as the definitive expression of the parties' intentions and agreements.

• Example 1: A Commercial Lease Agreement

  Imagine a small business owner signs a lease for a new office space. The written lease agreement clearly states that the tenant is responsible for all utility costs, including electricity and water. Later, a dispute arises because the business owner claims the landlord verbally promised during a tour that utilities would be included in the rent for the first year. Applying the "four corners" principle, a court would look only at the written lease. Since the lease explicitly assigns utility responsibility to the tenant and makes no mention of a utility-inclusive period, the alleged verbal promise would likely be disregarded because it falls outside the written document.

• Example 2: A Last Will and Testament

  Consider a person who creates a will that clearly states their entire estate is to be divided equally between their two children. After their passing, a close family friend comes forward, claiming the deceased had always expressed an intention to leave them a valuable antique watch, based on numerous conversations over the years. Under the "four corners" rule, a probate court would primarily examine the written will. If the will makes no mention of the antique watch going to the family friend, the court would likely disregard the friend's testimony about the deceased's verbal intentions, as those intentions were not formally included within the written document.

• Example 3: A Software Licensing Agreement

  A technology company enters into a written agreement to license its software to a client. The agreement specifies the software features included and the duration of the license. After a few months, the client demands access to an additional premium feature, stating that a sales representative had assured them during a product demonstration that this feature would be part of their package. If the written licensing agreement does not list this premium feature, the "four corners" principle would guide the interpretation. The court would focus solely on the terms written in the signed agreement, and the alleged verbal assurance from the sales representative would be considered extrinsic evidence and likely not used to alter the terms of the written contract.