Written description requirement
Also called written description, 112(a) written description, possession requirement, adequate written description, lack of written description
Written description requirement is the rule in 35 U.S.C. 112(a) that the specification must contain a written description of the invention1. It is separate from enablement: the Federal Circuit, sitting en banc in Ariad v. Eli Lilly, held that the statute contains a written description requirement separate from enablement2.
The test is whether the disclosure reasonably conveys to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date2. The USPTO applies the requirement under MPEP 21633.
The test: possession shown in the disclosure
- The statute says the specification shall contain a written description of the invention, and of the manner and process of making and using it, in terms that enable a person skilled in the art to make and use it (35 U.S.C. 112(a))1.
- In Ariad, the en banc court said the test is whether the disclosure of the application relied upon reasonably conveys to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date2.
- The court preferred the phrase "possession as shown in the disclosure". The test is an objective inquiry into the four corners of the specification from the perspective of a person of ordinary skill in the art2.
- Actual possession or reduction to practice outside the specification is not enough: the specification itself must demonstrate possession2.
- The requirement does not demand any particular form of disclosure and does not require the specification to recite the claimed invention in haec verba. A description that merely renders the invention obvious does not satisfy it2.
The MPEP says an applicant shows possession by describing the claimed invention with all of its limitations, using such descriptive means as words, structures, figures, diagrams and formulas that fully set forth the claimed invention3. Possession may be shown by an actual reduction to practice, by showing that the invention was ready for patenting, or by describing distinguishing identifying characteristics3.
The level of detail required varies with the nature and scope of the claims and with the complexity and predictability of the relevant technology2. Compliance is a question of fact decided case by case3.
When the issue arises
| Situation | What the sources say |
|---|---|
| Original claims | There is a presumption that an adequate written description is present when the application is filed, and the examiner has the initial burden of showing why a skilled person would not recognize a description of the claimed invention. The issue can still arise, for example when a claim requires an essential or critical feature that is not adequately described and is not conventional or known in the art3 |
| New or amended claims | New or amended claims that introduce elements or limitations not supported by the as-filed disclosure violate the requirement. There is no in haec verba requirement, but added claims or limitations must be supported through express, implicit or inherent disclosure3 |
| Priority or benefit claims | The question arises in deciding whether a claimed invention is entitled to the benefit of an earlier filing date under 35 U.S.C. 119, 120, 365 or 3863 |
| Validity in court | A claim can be held invalid for lack of written description. In Ariad, the en banc court held the asserted claims invalid on that ground2 |
See Patent disclosure for how the specification is built, and Patent claim for the claims that it must support.
Written description vs enablement vs the EPC tests
In the US, the MPEP states that the written description requirement is separate and distinct from the enablement requirement3. It also quotes the Federal Circuit that conclusive evidence of a claim's enablement is not equally conclusive of that claim's satisfactory written description3. The EPC has no single provision with the same name. Its nearest concepts ask different questions.
| Rule | Question it asks | Where |
|---|---|---|
| Written description | Does the disclosure reasonably convey that the inventor had possession of the claimed subject matter at the filing date?2 | US, 35 U.S.C. 112(a)1 |
| Enablement | Is the specification in terms that enable a person skilled in the art to make and use the invention?1 | US, 35 U.S.C. 112(a)1 |
| Added matter | Does an amendment introduce subject-matter extending beyond the content of the application as filed?4. An amendment is unallowable if the skilled person is presented with information not directly and unambiguously derivable from the application as filed, taking account of what is implicit7 | Europe, Article 123(2) EPC4 |
| Sufficiency of disclosure | Does the application disclose the invention clearly and completely enough for a skilled person to carry it out?5 | Europe, Article 83 EPC5 |
| Support for the claims | Are the claims clear, concise and supported by the description?6 | Europe, Article 84 EPC6 |
Article 123(2) and Article 83 are different tests. The first compares an amendment with the application as filed4,7. The second asks whether the skilled person can put the invention into practice, which in the EPO Guidelines means describing at least one way of carrying it out and disclosing any feature essential for doing so5,8. In the US, the written description requirement is also the basis for checking whether new or amended claims are supported by the as-filed disclosure3, which is the job Article 123(2) does in Europe4.
How it looks by jurisdiction
United States
- The specification must contain a written description of the invention (35 U.S.C. 112(a))1.
- The Federal Circuit holds that 35 U.S.C. 112, first paragraph (now 112(a)), contains a written description requirement separate from enablement (Ariad v. Eli Lilly, en banc, 2010)2.
- The USPTO's guidelines for examiners are in MPEP 21633.
Europe
- The European patent application or patent may not be amended so that it contains subject-matter which extends beyond the content of the application as filed (Article 123(2) EPC)4.
- The application shall disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art (Article 83 EPC)5.
- The claims shall be clear and concise and be supported by the description (Article 84 EPC)6.
China
- The description of an invention or utility model must be clear and comprehensive enough to enable a person skilled in the relevant field to carry it out (Patent Law of the PRC, Article 26)9.
- An amendment to an invention or utility model application may not go beyond the scope of disclosure contained in the original description and claims (Article 33)9.
- The claims shall be based on the description and define the scope of protection clearly and concisely (Article 26)9.
Seen in the record
The Federal Circuit's en banc decision is the leading case on whether 35 U.S.C. 112(a) has a separate written description requirement2. The decision is cited for the legal standard; it says nothing about either party beyond the record.
Ariad Pharmaceuticals, Inc. v. Eli Lilly and Company
The court held that 112, first paragraph, contains a written description requirement separate from enablement, and held the asserted claims of the '516 patent invalid for lack of written description2.
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Start draftingQuestions people ask
Is the written description requirement the same as enablement?
No. In the US, they are separate requirements of 35 U.S.C. 112(a)1. The MPEP calls the written description requirement separate and distinct from enablement3, and the Federal Circuit confirmed this en banc in Ariad2.
Must the specification use the exact words of the claim?
No. The Federal Circuit says the requirement does not demand that the specification recite the claimed invention in haec verba2. The MPEP adds that newly added claims or limitations must still be supported through express, implicit or inherent disclosure3.
Can an original claim fail the written description requirement?
Yes. There is a presumption that an adequate written description is present at filing, but the issue can arise even for original claims, for example when a claim requires an essential or critical feature that is not adequately described3.
Does the EPC have a written description requirement?
Not under that name. The nearest concepts are Article 123(2) EPC on added matter, Article 83 EPC on sufficiency of disclosure and Article 84 EPC on support for the claims4,5,6. Article 123(2) and Article 83 are different tests: one compares an amendment with the application as filed, the other asks whether the skilled person can carry out the invention5,7,8.
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