Define: Ab Initio

Ab Initio
Ab Initio
Quick Summary of Ab Initio

From Latin, meaning from the beginning. Applicable to original documents that do not comprise experimental data.

“Ab initio” is a Latin term meaning “from the beginning.” In UK law, it is commonly used to refer to actions or events that are considered void or invalid from their inception. When an agreement, contract, or legal proceeding is declared ab initio, it is treated as though it never existed, and the parties are restored to their original positions as if the transaction had never occurred. This principle is often invoked in cases of fraud, mistake, or illegality, where the underlying basis for the agreement or action is found to be fundamentally flawed or unlawful. By declaring an action ab initio, the legal system seeks to uphold integrity, fairness, and the rule of law by nullifying transactions tainted by fraud, deception, or other forms of misconduct.

What is the dictionary definition of Ab Initio?
Dictionary Definition of Ab Initio

Latin: “from the beginning.” Refers to documents that are original and composed without experimental data.

Full Definition Of Ab Initio

[Latin, From the beginning; from the first act; from the inception.] An agreement is said to be “void ab initio” if it has at no time had any legal validity. A party may be said to be a trespasser, an estate said to be good, an agreement or deed said to be void, or a marriage or act said to be unlawful, ab initio. Contrasted in this sense with ex post facto, or with postea.

The illegality of the conduct or the revelation of the real facts makes the entire situation illegal ab initio (from the beginning), not just from the time the wrongful behaviour occurs. A person who enters property under the authority of law but who then by misconduct abuses his or her right to be on the property is considered a trespasser ab initio. If a sheriff enters property under the authority of a court order requiring him to seize a valuable painting, but instead he takes an expensive marble sculpture, he would be a trespasser from the beginning. Since the officer abused his authority, a court would presume that he intended from the outset to use that authority as a cloak from under which to enter the property for a wrongful purpose. This theory, used to correct abuses by public officers, has largely fallen into disuse.

Ab Initio FAQ'S

Ab Initio” is a Latin term used in legal contexts to indicate something that is considered to have been true or valid from the beginning or inception of a particular event or legal process.

In UK Law, “Ab Initio” may be used to describe situations where an action or decision is retroactively invalidated or treated as if it never occurred, starting from the initial moment of the event.

An example of “Ab Initio” in UK Law could be the nullification of a contract due to a fundamental flaw or illegality discovered after its formation. In such cases, the contract may be deemed void ab initio, meaning it is treated as if it never existed, and parties are restored to their pre-contractual positions.

Yes, “Ab Initio” is a concept commonly encountered in various areas of UK legal practice, including contract law, administrative law, and criminal law, particularly in cases involving the retroactive nullification of legal actions or decisions.

When a decision or action is declared void ab initio, it is considered null and void from the outset, which means that any legal consequences or obligations arising from the action are effectively erased. Parties are generally restored to their positions as if the action had never taken place.

Yes, a court has the authority to declare a contract void ab initio if it determines that the contract is fundamentally flawed, illegal, or against public policy. This nullification typically results in the parties being released from their contractual obligations and reverting to their pre-contractual positions.

While “Ab Initio” is a powerful legal concept, its application may be subject to certain limitations and exceptions depending on the specific circumstances of each case and the relevant legal principles governing the matter at hand.

Yes, decisions declaring actions or contracts void ab initio can be challenged in court through legal proceedings, particularly if there are disputes regarding the validity or interpretation of the underlying legal principles or evidence relied upon in making the decision.

Parties can protect themselves from the risk of “Ab Initio” consequences in contracts by ensuring that the terms and conditions of the contract comply with applicable laws, regulations, and legal principles. Seeking legal advice and conducting thorough due diligence before entering into contracts can help mitigate the risk of later nullification.

Legal textbooks, case law analyses, and academic articles may provide further insights into the concept of “Ab Initio” and its application in UK Law. Additionally, consulting with legal experts or attending legal seminars and workshops may offer valuable opportunities to deepen your understanding of this legal principle.

Related Phrases
No related content found.

This site contains general legal information but does not constitute professional legal advice for your particular situation. Persuing this glossary does not create an attorney-client or legal adviser relationship. If you have specific questions, please consult a qualified attorney licensed in your jurisdiction.

This glossary post was last updated: 29th March 2024.

Cite Term

To help you cite our definitions in your bibliography, here is the proper citation layout for the three major formatting styles, with all of the relevant information filled in.

  • Page URL:
  • Modern Language Association (MLA):Ab Initio. DLS Solicitors. May 20 2024
  • Chicago Manual of Style (CMS):Ab Initio. DLS Solicitors. (accessed: May 20 2024).
  • American Psychological Association (APA):Ab Initio. Retrieved May 20 2024, from website:
Avatar of DLS Solicitors
DLS Solicitors : Divorce Solicitors

Our team of professionals are based in Alderley Edge, Cheshire. We offer clear, specialist legal advice in all matters relating to Family Law, Wills, Trusts, Probate, Lasting Power of Attorney and Court of Protection.

All author posts