in law, when something is true "from the beginning" of the act rather than when the court rules that it happened.
Ab initio Details
Ab initio is a term in legalese (language law professionals use) and is Latin for "from the beginning." It also translates to "from the first act" and "from inception." There are several instances when ab initio applies. One of the more common applications of the term is when describing void contracts and agreements that were never legal in the first place. If someone enters a property they have no right to enter, they are a trespasser ab initio. If someone gets married without the proper documentation, the marriage is void ab initio.
You can't declare something ab initio without proper evidence, however. The defendant or plaintiff must present a valid argument, e.g., the document was forged. This can be the case with a will. If the plaintiff wishes to argue that a will is void ab initio, they can argue that the grantor never signed a will, nor did a witness. They may also argue that a contract is one-sided, or is an unconscionable agreement—a party signed it because they were pressured to. If the court rules that the contract is an unconscionable agreement or signed under duress, they'll rule it void ab initio.
Because a contract is void from the start of the act, there is no way to remedy the situation. It is and always has been a void contract. Technically, the contract never even existed!
Ab initio Example
Ryan is headed to his first job interview since he was laid off five months ago. He needs the job; he needs the money and is on the verge of losing his apartment if he can't pay next month's rent. Even though he is a bit unsure of the work he'll have to do, he feels he has no choice. After arriving at the interview, the boss leads him into the office and shuts the door. Ryan notices that he's holding a folder and starts thinking that he may already have the job.
The interview is going very well for Ryan when the boss changes gears and takes out a contract from the folder. The boss explains that he needs to agree to the contract's terms and sign it for him to hire Ryan for the job. The terms include Ryan work every Saturday, every holiday, and that he does not file worker's compensation should he be injured on the job. This raises every red flag in the book for Ryan, but he just can't walk away from the job—he's desperate. The boss starts pressuring Ryan to sign the contract and plays on his desperation. Ryan eventually caves and signs.
A few weeks later, Ryan is injured on the job and files worker's compensation. After the company denies the claim, Ryan decides to take it to court. His boss brings up the contract he signed, but Ryan argues that he signed it under duress. Considering all the facts, the court rules in Ryan's favor and declares the contract void ab initio.