During the drafting stage of a patent specification, the question often arises as to how much information should be included in the detailed description for enablement purposes. Of course, it is important to include substantial information relating to each of the “essential features” of the invention, which are those feature that either support the claims or provide a clear enough and complete enough description of the invention and (for Australian law purposes) the best method then-known of performing it – especially those features that give rise to the advantages of the invention over and above the prior art. However, often it is not feasible or practical to add a highly detailed description of each and every feature mentioned in the patent specification, as Applicants would need to reproduce large amounts of published text to show the variants known in the prior art, causing patent specifications to run to hundreds of pages in length. This is a particular issue for inventions in the chemical and life sciences fields, where precise descriptions can involve extremely voluminous detail of chemical and structural features, and the permutations or specific variations can number in the thousands or millions (or more).

To circumvent (or at least mitigate) this issue, patent attorneys often adopt a shorthand, which is to “incorporate [published prior art documents] by reference”. The Australian Patent Examiner’s Manual notes that “cross-references to other documents merely to provide background information or prior art, or to illustrate subsidiary features, are not objectionable provided that … the cross-referenced document … was publicly available on or before the filing date of the specification referring to it”.^[1]  The generally accepted practice is for attorneys also to explicitly incorporate by reference material from the priority patent application(s) and the parent patent to the child, grandchild, great grandchild, etc, in case there is any subject matter that has been inadvertently omitted along the way, but becomes important later in prosecution.

The Australian Examiner’s Manual notes that the rules of construction for prior art citations are the same as those that apply to the construction of patent specifications.^[2] The principles relevant to construction of patents, and in particular, incorporation by reference of other documents, focus on the purpose of the incorporation. In other words, it is permissible to incorporate by reference another patent (or other patents) into a prior art patent (or into the patent specification) where the cross-referencing system has been adopted. However, the mere fact that one document is referred to in a second document does not automatically justify a claim that the second document is intended by its author to be read with the first document so as to form one consistent whole.

In all cases, the context and purpose of incorporating a document by reference (and of any further cross-referencing) is crucial to the nature and extent of information that is in fact brought across from the referenced document to the patent specification under consideration. This can include factors such as whether the document incorporated by reference teaches away from the claimed invention, or whether the incorporated document is in the same (or a related) field. The requirement appears to be that the author of the second document must have incorporated the contents of the earlier document into the later document in order to form one single source of information. An important factor is also how the skilled addressee would regard the document incorporated by reference into the patent.

Issues in patent prosecution

Various issues can arise from the practice of “incorporation by reference” during patent prosecution. In particular, an Examiner will often object during prosecution when a document is explicitly incorporated by reference to avoid disclosing matter which is required in order to perform the invention in any of the forms that are claimed. In this case, an amendment is often required to insert the relevant cross-referenced material before the application could be accepted.

Also, in the event that there is doubt as to the content of a referenced document, for example in the case of non-patent documents or if the cross-referenced document is not in English, evidence may be required to establish its disclosure at the filing date of the complete specification before a proposed amendment to explicitly incorporate the matter can be allowed.

As there is little doubt as to the content a published peer-reviewed journal article, or a published book, these kinds of documents would not tend to attract objections by an Examiner. However, the content of a website may be problematic, as its content can be subject to amendment over time, in which case it would be preferable to simply include the information into the patent specification rather than relying on a cross-reference. In any event, it is important to be clear what is being incorporated, either wholly or in part (in which case, which parts), and the specifics of the publication particulars (i.e., book edition, volume, pages, publication date, etc).

Key takeaways

1. Cross-references to other documents merely to provide background information or prior art, or to illustrate subsidiary features, are not objectionable provided that the document was publicly available on or before the filing date of the complete specification.
2. When a document is explicitly incorporated by reference to avoid disclosing matter which is required in order to perform the invention in any of the forms that are claimed, an amendment is required to insert the relevant cross-referenced material before the application can be accepted.
3. In the event that there is doubt as to the content of a referenced document, evidence may be required to establish its disclosure at the filing date of the complete specification before an amendment to incorporate the matter can be allowed.
4. It is preferable to include the actual text/drawings from the referenced document that is essential to understanding or performing the invention, rather than relying on incorporation by reference.
5. If a document incorporated by reference is essential to understanding or performing an invention, ensure that it is referred to and described in the priority application.
6. Applicants should ensure that the disclosure in any divisional application includes the disclosure of any parent or ancestor applications by using an explicit incorporation by reference.