Katoomba Real Estate Lawyer, Australia, page 3

(1) A legal principle that prevents a person from asserting or denying something in court that contradicts what has already been established as the truth. equitable estoppelA type of estoppel that bars a person from adopting a position in court that contradicts his or her past statements or actions when that contradictory stance would be unfair to another person who relied on the original position. For example, if a landlord agrees to allow a tenant to pay the rent ten days late for six months, it would be unfair to allow the landlord to bring a court action in the fourth month to evict the tenant for being a week late with the rent. The landlord would be estopped from asserting his right to evict the tenant for late payment of rent. Also known as estoppel in pais.estoppel by deedA type of estoppel that prevents a person from denying the truth of anything that he or she stated in a deed, especially regarding who has valid ownership of the property. For example, someone who grants a deed to real estate before he actually owns the property can't later go back and undo the sale for that reason if, say, the new owner strikes oil in the backyard.estoppel by silenceA type of estoppel that prevents a person from asserting something when she had both the duty and the opportunity to speak up earlier, and her silence put another person at a disadvantage. For example, Edwards' Roofing Company has the wrong address and begins ripping the roof from Betty's house by mistake. If Betty sees this but remains silent, she cannot wait until the new roof is installed and then refuse to pay, asserting that the work was done without her agreement.estoppel in paisSee equitable estoppel.promissory estoppelA type of estoppel that prevents a person who made a promise from reneging when someone else has reasonably relied on the promise and will suffer a loss if the promise is broken. For example, Forrest tells Antonio to go ahead and buy a boat without a motor, because he will sell Antonio an old boat motor at a very reasonable price. If Antonio relies on Forrest's promise and buys the motorless boat, Forrest cannot then deny his promise to sell John the motor at the agreed-upon price.(2) A legal doctrine that prevents the relitigation of facts or issues that were previously resolved in court. For example, Alvin loses control of his car and accidentally sideswipes several parked cars. When the first car owner sues Alvin for damages, the court determines that Alvin was legally drunk at the time of the accident. Alvin will not be able to deny this fact in subsequent lawsuits against him. This type of estoppel is most commonly called collateral estoppel.

A valid contract in which a copyright owner authorizes another person or entity (called the licensee) to exclusively exercise one or more of the rights (or portion of such rights) that belong to the copyright owner under the copyright. The licensee is said to 'own' the rights granted in the license and is referred to as a copyright owner.

A work created by an employee within the scope of employment or a work commissioned an author under contract. With a work for hire, the author and copyright owner of a work is the person who pays for it, not the person who creates it. The premise of this principle is that a business that authorizes and pays for a work owns the rights to the work. There are two distinct ways that a work will be classified as 'made for hire.'the work is created by an employee within the scope of employment; or the work is commissioned, is the subject of a written agreement, and falls within a special group of categories (a contribution to a collective work, a part of a motion picture or other audiovisual work, a translation, a supplementary work, a compilation, an atlas, an instructional text, a test, or as answer material for a test). The work made for hire status of a work affects the length of copyright protection and termination rights.

Language used to leave property to a person and his or her descendants, which typically take the form 'to A, and the heirs of his body,' where A is the person receiving the property.

A legally binding contract in which a person or business promises to treat specific information as a trade secret and not disclose it to others without proper authorization. Nondisclosure agreements are often used when a business discloses a trade secret to another person or business for such purposes as development, marketing, evaluation or securing financial backing. Although nondisclosure agreements are usually in the form of written contracts, they may also be implied if the context of a business relationship suggests that the parties intended to make an agreement. For example, a business that conducts patent searches for inventors is expected to keep information about the invention secret, even if no written agreement is signed, because the nature of the business is to deal in confidential information.

A doctrine that prevents a defendant from re-litigating an issue after it has been lost. For example, if your neighbor sues you for putting up a fence on his land and the court rules that your fence extends beyond your property line, you can't later file your own lawsuit seeking a declaration that the property line is incorrectly drawn.

A provision in a contract stating that some or all of the terms of the contract will be altered or voided by the occurrence of a specific event. For example, a contingency in a contract for the purchase of a house might state that if the buyer does not approve the inspection report of the physical condition of the property, the buyer does not have to complete the purchase.

An unforeseen and uncontrollable event that excuses a party to a contract from performing his or her duties under that contract. For example, a landlord can break a lease if the property she agreed to rent accidentally burns down before the tenants move in.