If a prior art device performs all functions of an apparatus claim, what is true about the prior art?

The statement about prior art claiming to anticipate an apparatus claim is best understood by looking closely at the definition of anticipation within patent law. Anticipation occurs when a single prior art reference discloses each and every element of a claimed invention as arranged in the claim. Therefore, if a prior art device performs all the functions of an apparatus claim but has structural differences, it does not meet the necessary criteria to be considered identical in claim scope.

For a prior art reference to fully anticipate a claim, it must demonstrate all elements in the same manner as the claimed invention. Structural differences, even if the functions are the same, indicate that the device does not fully embody the claimed apparatus. This is critical in patent law because it allows for innovation without infringement, provided that the new device incorporates significant structural modifications that impart its novelty.

In this context, prior art can indeed be relevant to assessing infringement but cannot anticipate a claim if it contains structural differences. The presence of a prior art device that performs the same functions but does not match structurally highlights the distinct nature of the claimed invention, thereby allowing it to be patented if it demonstrates sufficient novelty.