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 anticipates a patent claim.[1] The rule is also applicable to an obviousness analysis.[2] 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 and every claimed element.
The term elements generally refers to the parts of a device accused of infringement, while the term limitations refers to the defining properties of the claimed device or invention.[3]
For example, consider this notional claim:
A tool for driving nails into a piece of wood, said tool comprising:
- a longitudinally extended wooden handle having a proximal end adapted to be grasped by a human hand and a distal end; and
- an iron head attached to said distal end of said handle, said head extending normal to said handle and having a first outer end and a second outer end, each said outer end distanced from said handle, said first outer end having a claw integral therewith and said second outer end having a flat distal face.
The elements of this claim include the handle, the head, the claw, and the face. The limitations include that there is a handle and it is wooden, it is longitudinally extended, its proximal end is adapted to be grasped by a human hand; that there is a head and it is iron; and that there is a claw part of the head and a face part of the head, and the claw is integral with the face.
Under the all-elements rule, the claim is anticipated only if a single reference discloses each and every claimed element (or an equivalent of it). Under the more precise all-limitations rule now preferred in the United States Court of Appeals for the Federal Circuit,[4] the claim is anticipated only if a single reference discloses each and every claimed limitation (or an equivalent of it).[5]
A corollary to the all-limitations rule is that the doctrine of equivalents cannot be employed in a manner that wholly vitiates or nullifies a claim limitation.[6] Thus, a bronze hammer head might be found to be "equivalent" to the literally-claimed iron head, while a Styrofoam head would likely not be found equivalent; the issue is whether the new material (bronze or Styrofoam) differs "substantially" from the iron material literally recited in the claim. In deciding whether a material is substantially different from that literally recited in a patent claim, a court can use statements in the patent itself.[7]