In regard to the question of whether there still is a need for both the written description requirement and the claim requirement, while the written description provides support (both enablement and possession) for the claims, the claims define the invention and play a critical role in determining infringement. A patent must describe the exact scope of the invention to give the applicant all that he or she is entitled and to notify the public of what is still open to future inventors. These objectives are served by both the specification, which describes the invention in such full, clear, concise, and exact terms as to enable any person skilled in the art to make and use the invention; and, the patent claims, which define the scope of the patent grant and function to forbid not only exact copies of the invention, but products that go to the heart of the invention yet avoid the literal language of the claims by making a trivial change.98

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In determining when a court will find that a written description does or does not support a claim, it is helpful to review prior case law. It is important to remember, however, that this determination is a factual one made by the court on a case-by-case basis.99 Additionally, to avoid ambiguity when referring to the written description requirement, courts in their opinions should explicitly distinguish between the written description (possession) requirement and the enablement requirement.

Overall, the written description requirement of the Patent Act promotes the progress of the useful arts by ensuring applicants adequately describe their inventions in the specification for the benefit of the public in exchange for the right to exclude others from practicing the invention during the life of the patent.