Campbell Hall Landlord-Tenant Lawyer, New York, page 2

Principles of international law so fundamental that no nation may ignore them or attempt to contract out of them through treaties. For example, genocide and participating in a slave trade are thought to be jus cogens.

(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 commercial real estate lease in which the tenant regularly pays not only for the space (as he does with a gross lease) but for a portion of the landlord's operating costs as well. When all three of the usual costs--taxes, maintenance and insurance--are passed on, the arrangement is known as a 'triple net lease.' Because these costs are variable and almost never decrease, a net lease favors the landlord. Accordingly, it may be possible for a tenant to bargain for a net lease with caps or ceilings, which limits the amount of rent the tenant must pay. For example, a net lease with caps may specify that an increase in taxes beyond a certain point (or any new taxes) will be paid by the landlord. The same kind of protection can be designed to cover increased insurance premiums and maintenance expenses.

(1) A lack of physical or mental abilities that results in a person's inability to manage his or her own personal care, property or finances. (2) A lack of ability to understand one's actions when making a will or other legal document. (3) The inability of an injured worker to perform his or her job. This may qualify the worker for disability benefits or workers' compensation.

A legal doctrine stating that if a person receives money or other property through no effort of his own, at the expense of another, the recipient should return the property to the rightful owner, even if the property was not obtained illegally. Most courts will order that the property be returned if the party who has suffered the loss brings a lawsuit.

A meeting of the minds. An agreement is made when two people reach an understanding about a particular issue, including their obligations, duties and rights. While agreement is sometimes used to mean contract -- a legally binding oral or written agreement -- it is actually a broader term, including understandings that might not rise to the level of a legally binding contract.

Property that is subject to use by another for a specific purpose. For example, a beachfront house that has a public walkway to the beach on its premises would be a servient tenement.

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.