Roscoe Real Estate Lawyer, Pennsylvania

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.

A contract giving written permission to use an invention, creative work or trademark. A license provides a way to make money from your invention or creative work without having to manufacture and sell copies yourself. By licensing an invention or work to a company, you get money (often in the form of royalties) in return for allowing the company to use, produce and sell copies of your invention or work in the marketplace.

When a landlord provides housing that is so substandard that a landlord has legally evicted the tenant. For example, if the landlord refuses to provide heat or water or refuses to clean up an environmental health hazard, the tenant has the right to move out and stop paying rent, without incurring legal liability for breaking the lease.

A remedy provided by a court that orders the losing side to perform its part of a contract rather than, or possibly in addition to, paying money damages to the winner.

The terms of your contract with an airline after you buy a ticket. Conditions of carriage cover everything from baggage limitations to the amount of compensation you can recover if you're injured on the flight. These provisions often vary from airline to airline. A few, but by no means most, conditions of carriage appear in the fine print on the back of your ticket. To find out about the rest, you can ask the airline for a copy; it is legally obligated to provide one. The conditions of carriage contain a lot of fine print detail and will not make for exciting reading.

A guarantee about the quality of goods or services made by a seller, such as 'This item is guaranteed against defects in construction for one year.' Most express warranties come directly from the manufacturer or are included in the sales contract. If you want to hold the seller to an oral guarantee, it's best to get it in writing or have witnesses to the guarantee so that it doesn't come down to your word against the seller's if a problem arises.

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.

A legally binding agreement involving two or more people or businesses (called parties) that sets forth what the parties will or will not do. Most contracts that can be carried out within one year can be either oral or written. Major exceptions include contracts involving the ownership of real estate and commercial contracts for goods worth $500 or more, which must be in writing to be enforceable. (See statute of frauds.) A contract is formed when competent parties -- usually adults of sound mind or business entities -- mutually agree to provide each other some benefit (called consideration), such as a promise to pay money in exchange for a promise to deliver specified goods or services or the actual delivery of those goods and services. A contract normally requires one party to make a reasonably detailed offer to do something -- including, typically, the price, time for performance and other essential terms and conditions -- and the other to accept without significant change. For example, if I offer to sell you ten roses for $5 to be delivered next Thursday and you say 'It's a deal,' we've made a valid contract. On the other hand, if one party fails to offer something of benefit to the other, there is no contract. For example, if Maria promises to fix Josh's car, there is no contract unless Josh promises something in return for Maria's services.

A statement included in a patent application that describes the structure of an invention in precise and exact terms, using a long established formal style and precise terminology. Patent claims serve as a way for the U.S. Patent and Trademark Office (PTO) to determine whether an invention is patentable, and as a way for a court to determine whether a patent has been infringed. In concept, a patent claim marks the boundaries of the patent in the same way as the legal description in a deed specifies the boundaries of the property.