All elements test

The all elements rule or all limitations rule (often written with a hyphen after "all") is a legal test used in US patent law to determine whether a given reference shows that a patent claim lacks the novelty required to be valid. The rule is also applicable to an obviousness analysis. Under the rule, a single reference (for anticipation) or the combination of references relied upon (for obviousness) -- plus the ordinary knowledge of persons skilled in the art -- must explicitly or implicitly provide each claimed element.