The Best Mode Requirement

What You Need To Understand About It.

The Best Mode Requirement. Why your written description should include your preferred mode of performing your invention.

The best mode is the third in our series of articles about the first little paragraph about the patent specification found in 35 USC ยง 112. We earlier wrote about the written description, and then about the enablement requirement. That first paragraph says:

The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.

The part we will focus on here is:

The specification......shall set forth the best mode contemplated by the inventor of carrying out his invention.

So what is this part about?

One of the underlying premises of patent law is that the inventor is trying to obtain the right to exclude others from practicing the claimed invention. The government will grant that limited term right but in exchange the inventor must fulfill certain requirements. In this particular requirement the inventor is required to disclose his/her preferred mode for performing the invention at the time the application was filed.

Now let's explore this. At the time of filing, the inventor will probably know several ways of achieving the invention, and one of them may well be his/her preferred one. The inventor is then required to disclose that best mode. This requirement is a safeguard against a natural desire of some people to obtain patent protection without making a full disclosure as required by US patent law.

As in our earlier exploration of the written description requirement and the enablement requirement we find that the real meaning of this requirement and how it is interpreted has been refined over the years by case law - that is in court cases. I don't like to quote case law because it can be very tedious - but let's explore some implications of various rulings so you will know what you have to do - and what you do not have to do.

Is Active Concealment the Only Behavior That Can Invalidate a Patent?

No. When an inventor knows for example that a specific ingredient in a formulation gives the best result but only discloses that ingredient in a general way, this requirement has not been satisfied.

Example - a best formulation requires lithium bromide and it works better than lithium chloride or lithium fluoride, but the written description only discloses the broader category of the lithium halides - so best mode requirement has not been satisfied.

Do You Have to Point Out the Best Way?

No. The only requirement is that the best way is disclosed. You can describe five different modes, but you do not have to point out that the third one is the best. But one of them should be your best way (at the time of filing).

What If I Discover a Better Mode a Week After Filing?

There is no requirement to update the best way based on later discoveries.

How Will the Examiner Know?

This question has probably already occurred to you. Frankly, the information that is necessary for the examiner to recognize a best mode infraction is rarely available to the examiner. The examiner cannot examine your inventor notebooks, your internal documents, your e-mails, etc. The best the examiner can do is by careful reading of your disclosure whether you knew that one mode was superior to another, and if so whether you then disclosed that mode well enough to enable one of ordinary skill in the art to practice that preferred mode. In my years of practice I have never had an examiner challenge me on this requirement.

But you should go out of your way to ensure that your preferred mode is disclosed - first because it is the law and the right thing to do, but secondly because all of those other sources (inventor notebooks, internal documents, e-mails, etc) are often easily uncovered during discovery procedures in patent litigation, interference practice, or other legal proceedings. And again - in my more limited experience of litigation I always see attorneys representing the party being sued for infringement go after best mode issues with a vengence. Every notebook, memo, and e-mail will be scrutinized.

So don't take best mode lightly - discuss it with your patent prosecutor during the drafting of your application so that your prosecutor knows your best mode, and be sure it gets included.

As in written description and enablement - there are further subtle issues in this requirement. But we will not go into them here. If perhaps you want a little deeper understanding of what constitutes either satisfying or not satisfying the best mode requirement this section in the MPEP (Manual of Patent Examination Procedures) will be helpful. It gives several examples from case law in which the final ruling was either that the requirement was satisfied or not.


The Best Mode Requirement
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Mike Ervin
Mike Ervin - Cost Effective Small Business Patent Protection.

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