During the process of patent granting and patent invalidation procedures, patent applicants and patentees typically focus on how to obtain a granted patent or how to maintain patent validity. For this purpose, the applicant or patentee will often amend claims or descriptions or submit observations to explain or clarify the scope of protection. Under the principle of estoppel, such amendments and observations will in fact have an impact on the future enforcement of patent rights and, more seriously, may directly lead a court to conclude non-infringement. Here, this article will briefly discuss possible impacts of amendments and observations submitted during the patent prosecution or patent invalidation procedures on the future enforcement of patent rights and put forward some suggestions, in combination with the 2018 second instance final judgment of an actual case. The first-instance judgment in the case was also named one of the top ten typical cases of 2017 of the Guangzhou Intellectual Property Court.

The principle of estoppel applies in cases where a patentee restricts the scope of patent protection in order to obtain a granted patent or maintain the validity of a patent in the process of patent prosecution. Indicating that certain content is excluded from the scope of protection during patent prosecution or patent invalidation procedures precludes the applicant or patentee from re-incorporating such content into the scope of protection in a subsequent patent infringement lawsuit.

The Supreme People's Court officially sets out the principle of estoppel in Article 6 of the Interpretation on Several Issues Concerning the Application of Laws to the Trial of Patent Infringement Disputes I: “Where the patent applicant or patentee has abandoned a technical solution through amendments to claims and/or specification or observations during the prosecution or invalidation process, if the patentee asserts in a patent infringement lawsuit that the extent of protection of the patent right should include the technical solution, the People’s Court shall not allow such an assertion.”

With regard to the abandonment of technical solutions, the Supreme People’s Court added a “clearly rejected” exception to the estoppel principle in Article 13 of the Interpretation on Several Issues Concerning the Application of Laws in the Trial of Patent Infringement Disputes II. Under this exception, only where an examiner has “clearly rejected” amendments or observations which are intended to narrow the protection scope of claims will relevant technical solutions not be considered abandoned and not give rise to the principle of estoppel

The main purpose of the principle of estoppel is to prevent the patentee from violating the principle of good faith, to “have it both ways” in the patent prosecution/invalidation process and infringement proceedings, resulting in harm to the public interest. In the course of the above case, the court used the previous patent examination dossier to explain the controversial technical features in the claims, in addition to the description, drawings, and the related claims in the claims of the subject patent. As can be seen, the work during the patent prosecution and patent invalidation procedures is also crucial for future rights protection.

The trial process of this case has many implications for patent applicants and intellectual property practitioners. During patent application, prosecution and patent invalidation procedures, we should keep estoppel in mind so as to avoid unnecessary troubles in the future enforcement of patent rights. Specifically, in order to avoid the impact of estoppel, applicants should pay more attention to the following aspects during patent prosecution:

Reasonably determine the scope of protection of independent claims and sufficiently lay out dependent claims before filing an application:

Fully provide the patent attorney with the background arts and innovative features of the invention so that the patent attorney can clarify the boundaries between the invention and the prior art, and thus the scope of protection of independent claims can be reasonably determined for the new, innovative features of the invention and dependent claims can be sufficiently and effectively laid out. The claims should be laid out in a manner from high-level to moderate generalizations and then to specific embodiments, so that all the technical solutions to be protected can be fully covered by the claims.

Carefully draft written communications with the State Intellectual Property Office in the patent prosecution and patent invalidation procedures:

During patent prosecution and patent invalidation procedures, it is prudent to draft written amendments and observations to be submitted, and to avoid carelessly interpreting invention technical solutions or amending claims in attempt to obtain a granted patent or maintain the validity of patent rights. In particular, when emphasizing that the technical solution of the invention differs from the cited references, or when amending the claim from a broader scope of protection to a narrower scope of protection, careful consideration should be given to whether such observations or amendments would lead to an abandonment of technical solutions which are actually desired to be contained in the scope of protection. In the patent prosecution process, for observations that may limit the scope of protection of the claims, you may consider contacting the examiner to verbally state the opinions in order to leave as little documentary evidence as possible while convincing the examiner.

Proactively clarify different opinions in the patent prosecution and patent invalidation procedures:

In the patent prosecution and patent invalidation procedures, if the patent applicant or patentee disagrees with the examiner's opinions, he should respond and explain in a positive manner, or alternatively, clearly and reasonably define or explain the relevant technical features in a desirable way in further amendments.

In summary, during patent prosecution and patent invalidation procedures, any amendments to the claims or description and any observations should be carefully considered to avoid unnecessary losses caused by the principle of estoppel.