Defending the Patent Case – Exploiting the Tensions in Patent Law in Inventor and Expert Depositions

Established principles of patent law require that the patent claims be interpreted in the same way for purposes of establishing patent infringement and patent invalidity. This requirement often produces a tension between the patent holder’s assertion that the patent is infringed and its assertion that its patent is valid.  Even when the patent holder is well-intentioned, it can be difficult to ensure that its infringement and invalidity positions are harmonized and consistent with one another.  As a result, an accused infringer can often exploit these tensions to extract helpful admissions, especially when the inventors or the patent holder’s experts are not sensitive to them.  When representing an accused infringer, it is important to identify these tensions as early in the case as possible so appropriate discovery strategies can be deployed to develop helpful admissions.

Here are some examples of situations where these tensions arise and how they can be used to extract helpful admissions.

Anticipation and Infringement

In many cases, prior art may surface which the patent holder cannot readily distinguish without making an argument that undercuts its infringement position.  This especially occurs when there is an inferential leap that the patent holder is making to establish that a certain claim element is present in the accused infringer’s product.  Often, that leap can only logically be made if the claims are applied in a way that causes them to read on the prior art (i.e., to be invalid for anticipation).  What is important to note is that the claim construction process often does not resolve these tensions because in many cases the construction may be agnostic to whether the claims should be applied in the way that they are being applied in the patent holder’s infringement analysis or its anticipation analysis. Patent holders typically deploy a strategy of seeking vanilla, tautological constructions that allow them to conceal inconsistent methods of applying the claims against accused products and the prior art.

In one scenario, a key piece of prior art does not expressly describe a particular claim element, and the presence of the element can only be established through the doctrine of inherent disclosure.  It is sometimes the case that the patent holder has to rely on a mode of analysis to establish that the accused product is practicing a particular claim element which, if appropriate, also establishes that the claim element is inherently present in the prior art.

When deposing an inventor or expert in a situation where this type of tension is present, it is helpful to misdirect the witness by asking questions directed to one issue, anticipation for example, which will elicit testimony that is helpful to the other issue, infringement for example.  You do this by identifying the witness’ natural inclination in answering questions, and exploiting it.

In one recent case we were involved in, the patent holder used two experts. One opined on infringement, and the other on invalidity.  The experts each applied the claims in ways that were contradictory, even though court’s claim constructions did not suggest one way or the other if either application of the claims was legitimate.  Having recognized this contradiction, we asked questions to the invalidity expert which suggested that the prior art anticipated the claims.  Of course, we knew he would not agree with us.  However, the testimony we elicited showed that the accused methods were not infringing.  In that case, we were able to use this strategy because the infringement expert used a prior art patent to show that the accused methods were practicing the claims.  The invalidity expert was naturally inclined to dispute any questions suggesting that the piece of prior art was anticipatory, and in so doing, gutted the patent holder’s infringement case.

Anticipation and Written Description

In some cases, there is an issue as to whether the originally-filed patent application (or a parent thereof) disclosed a particular claim feature. In such cases, the patent holder may try to show that the feature was inherently disclosed in the as-filed application because it is not expressly described.  Here again, the chain of reasoning and inferences used to establish that the feature was inherently present in the earlier filed application may also show that it was inherently disclosed in the prior art. By asking questions suggesting that the feature was not present in the earlier filed application, you may elicit answers showing that it was inherently disclosed in the prior art.

Obviousness and the Doctrine of Equivalents

Sometimes an accused product does not literally include a particular patent claim element, but it includes something that is similar.  Under certain circumstances, if the differences between the claim element and the corresponding feature in the accused product are “insubstantial”, the accused product may be found to infringe under the doctrine of equivalents.

Depending on the prior art, the patent holder’s positions on obviousness and the doctrine of equivalents may be in tension.  It may be the case that in arguing that the alleged equivalent in the accused product is substantially similar to the corresponding claim element, the patent holder effectively concedes that it would have been obvious to modify the prior art to obtain the claim element.

So, for example, if questioning an expert who opines that the claimed invention is not obvious over the prior art, you can ask questions that suggest the differences between the claim element at issue and the prior art are trivial.  The expert will likely push back and give a detailed explanation of why they are significantly different, providing you with good ammunition for establishing that the alleged equivalent in the accused product is not equivalent at all.  Depending on the specific nature of the prior art and the patent holder’s positions on infringement, you may want to go in the other direction and ask the expert or inventor questions that suggest that an alleged equivalent is very different from the claim element to which it corresponds, which may prompt a response that helps establish obviousness.  The key to picking one strategy over the other is determining how the witness is inclined to answer questions or asking some preliminary questions that suggest you are focusing on one issue (e.g., obviousness) so he is inclined to push back in a way that helps with the other issue (e.g., doctrine of equivalents).

Obviousness or Anticipation and Enablement

In some cases, the patent in suit is thin on implementation details, raising the question of whether it enables those skilled in the art to make and use the claimed invention.  In order for a piece of prior art to anticipate a patent claim (i.e., render it not novel), it must be enabled. However, patent holders need to be mindful that any criticisms they level at the prior art may apply equally to their patent.

In addition, patent holders may attempt to rebut an obviousness attack by arguing that they solved a challenge that was not previously solved.  However, if the details of the solution are not well described in the patent-in-suit, they may show that it is not enabled.  Therefore, questions suggesting that it would have been easy to combine or modify references to obtain the claimed invention, may provoke a response full of implementation challenges that the patent-in-suit does not itself address. Such answers may help establish that the patent is not enabled.

These are not one size fits all suggestions for all cases.  Whether any of these strategies will work in a given case depends on the nature of the patent holder’s infringement proof, the extent of the disclosure in the patent-in-suit, and the nature of the prior art.  In addition, the questions need to be crafted to elicit a response on one issue that will undercut the patent holder’s position on another issue.  However, in the types of cases that get litigated on the merits, these tensions are not at all uncommon, and the party that first recognizes and exploits them can significantly improve its chances of prevailing.