What is State Of The Art?

Legal Definition
State of the art (sometimes cutting edge) refers to the highest level of general development, as of a device, technique, or scientific field achieved at a particular time. It also refers to such a level of development reached at any particular time as a result of the common methodologies employed at the time. The term has been used since 1910, and has become both a common term in advertising and marketing, and a legally significant phrase with respect to both patent law and tort liability. In advertising, the phrase is often used to convey that a product is made with the best possible technology, but it has been noted that "the term 'state of the art' requires little proof on the part of advertisers", as it is considered mere puffery. The use of the term in patent law, by contrast, "does not connote even superiority, let alone the superlative quality the ad writers would have us ascribe to the term".
-- Wikipedia
Legal Definition
Total of technical and scientific knowledge that is currently available as applied to a product or design.