Defending the Patent Case: Discovery Primer on Interrogatories

This week, we follow-up on last week’s post on requests for production with a discussion of interrogatories. 

Before serving interrogatories, it is advisable to obtain all of the information you can about the topics below through publicly available information such as SEC filings, press releases, product brochures, patent office records, etc.  This information may help you better focus the interrogatories on those areas that are most likely to be productive.  You should also talk to your client to see what it knows about these subjects.

With interrogatories, you have a unique opportunity to elicit a narrative of the patent holder’s case.   They are an invaluable tool that you can use to minimize the likelihood of being surprised at trial by evidence or arguments that were not previously disclosed.  You will sometimes see parties file motions in limine to exclude from trial evidence and argument that were not disclosed in response to interrogatories and requests for production.

The importance of eliciting the patent holder’s case prior to trial is possibly more critical in patent cases than in other types of litigation.  The reason is that patent cases often have a significant amount of flexibility in the way that they are presented.  For example, a patent holder may elect to assert only certain of its patent claims.  It may also elect to argue infringement based on the doctrine of equivalents instead of literal infringement.  In addition, many times there is a tension between the manner in which the patent holder applies the claims to the accused product and the manner in which it distinguishes the claims from the prior art.  It is critical to get a clear understanding of how the claims are being applied to determine if there are inconsistencies and to determine whether there are any claim construction issues underlying the patent holder’s application of its claims which need to be resolved by the Court.

Patent holders also have a wide degree of latitude in forming their damages case.  They may pursue lost profits damages or reasonable royalty damages (or both).  They may seek damages based on “convoyed sales” of items typically sold in association with the patented product.   It is critical that you find out what damages theories are being pursued so you can develop the evidence necessary to rebut them.

Here are some suggestions for interrogatory topics:

Interrogatory Topics

         Contention Interrogatories

As the name suggests, these interrogatories seek to find out what the patent holder contends.  They are critical for forcing the patent holder to identify the basis of its case before trial so that you can develop your case and seek the appropriate discovery.

1.  Infringement Contentions. Before explaining what information should be sought, let me say that certain jurisdictions have mandatory infringement contention disclosure requirements (e.g., Northern District of California, Eastern District of Texas, and Northern District of Illinois).  In that case, you do not want to waste valuable interrogatories (you are limited to 25 in Federal Court) seeking information that the patent holder is already obligated to provide.  That said, there are some key pieces of information that you should seek:

 a.  An identification of the specific patent claims that the patent holder contends are infringed;

b.  An identification of the products that the patent holder contends are infringing; and

c.  The patent holder’s contentions as to which claim elements correspond to which features of the accused products.

You can also ask whether infringement is literal or by equivalents.  Item c is of particular importance for identifying which claim terms the court may need to construe because it will reveal the implicit definitions the patent holder is using in its infringement case. 

One word of warning here.  Some courts do not require responses to contention interrogatories until near or at the close of discovery.   In that case, you may have to evaluate the possible contentions and frame your discovery and claim construction strategies accordingly. However, many courts now realize that patent cases can be conducted much more efficiently by requiring patent holders to disclose their contentions earlier rather than later in the case.  Ultimately, you will also want to know what evidence the patent holder is relying on to establish infringement.  In theory, the patent holder should have that evidence before bringing the case to comply with Rule 11 of the Federal Rules of Civil Procedure.  However, courts are likely to give a patent holder some latitude and allow it to take discovery before requiring it to commit to the specific evidence on which it will rely.

2. Damages Contentions.  Here are some key things that you will want to know: 

a.  Is the patent holder pursuing a reasonable royalty or lost profits damages?

b.  How is the patent holder calculating damages?

c.  What evidence is the patent holder relying on to establish damages?

The damages case will typically be presented by an expert witness.  Thus, many patent holders may attempt to defer providing its damages contentions until after expert reports are due.  However, it is still important to serve damages contention interrogatories to ensure that they are obligated to fully disclose their damages case before trial.

3.  Date of Invention Contentions.  In current cases and those that will not be governed by the first to file provisions of the America Invents Act, the date of invention may be critical for determining whether a particular reference is or is not prior art.  For example, the date of invention –not the application filing date—will determine whether a particular reference qualifies as prior art under Sections 102(a) and 102(e) of the patent statute.  Thus, if the patent holder intends to prove a date of invention that pre-dates the filing of the application for the patent-in-suit, you will want to know what that date is and what evidence supports it.

4. Validity Contentions.  At some point in the case, your patent invalidity case will become clear.  For example, you will eventually identify key prior art references that you believe are invalidating or will have identified areas of indefiniteness, lack of enablement, or lack of written description.  At that point, it may be helpful to serve interrogatories that seek the patent holder’s responses to those contentions to determine how it will respond to them at trial.

 If you are asserting that the patent-in-suit is invalid for obviousness over the prior art, it is also important to determine if the patent holder will offer evidence of the “secondary considerations of non-obviousness” (e.g., commercial success, solving a long-felt but unsolved need, etc.) and what that evidence will be.

 I have seen accused infringers serve broad interrogatories that seek an explanation of why a patent is valid.  These may be objectionable because they require the patent holder to speculate as to what possible grounds of invalidity could be raised and to then rebut them.  It will likely be more productive to identify specific grounds of invalidity and seek the patent holder’s contentions as to them.  

            Non-Contention Interrogatories

            While contention interrogatories are essential, other types of interrogatories will help you identify fruitful areas for additional discovery.  Here are some suggested topics:

1.  A description of the development of the claimed invention.  This information may help you pursue evidence of improper inventorship, lack of enablement, and on-sale or public use bar invalidity.  Here are some key pieces of information to seek:

a.  The identity of all individuals involved in conceiving and reducing the claimed invention to practice.

b.  An identification of the documents that establish the conception and reduction to practice of the claimed invention.

c.  The timing of the conception and reduction to practice of the claimed invention.

d.  When the claimed invention was first sold, offered for sale, or publicly used.

One thing to look for in particular is information that was used to actually reduce the invention to practice but which was not included in the patent-in-suit.  Such information may provide a basis for arguing that the patent is not enabled.

 2.  A description of the patent holder’s commercial exploitation of the invention.  This information will be important for damages and may also be relevant to whether there is evidence of “secondary considerations of non-obviousness”.  Here are some things to seek:

a.  An identification of the patent holder’s commercial embodiments of the patent-in-suit.

b.  Sales figures for the patent holder’s commercial embodiments.

c.  Costs that are used to calculate profits for sales of the patent holder’s commercial embodiments.

d. An identification of individuals with knowledge of the patent holder’s commercial embodiments and sales/profit information.

Although it is arguably a contention interrogatory, it is also a good idea to request that the patent holder identify how the asserted patent claims correspond to its commercial embodiments.  It is important to make sure that the products the patent holder identifies actually fall within the scope of its claims, otherwise their sales and profit information is irrelevant.

3.  Information regarding foreign equivalents of the patent-in-suit.  The file histories of foreign counterparts may reveal prior art that was not disclosed to the U.S. Patent & Trademark Office.  You can often find out about foreign equivalents on-line.  However, on-line records may be incomplete.  Find out what applications were filed, what their status is (abandoned, issued, pending), and who was involved in prosecuting them.

4.  Licenses to the patent-in-suit or similar patents.  The terms of licenses to the patent-in-suit or to similar patents may be relevant to reasonable royalty damages calculations.  Ask the patent holder to identify any such licenses (and make sure to seek the actual licenses in requests for production).

5.  Prior lawsuits on the patent-in-suit.  This information is usually publicly available nowadays. However, you may want to request that the patent holder identify other cases in which it asserted that its patent was infringed.  The defendants in those cases may be interested in helping you defend your case or willing to provide helpful leads.

 A final piece of advice: Keep in mind the 25 interrogatory limit and always save some interrogatories for use later in discovery.  You never know what may develop, and you will not want to be foreclosed from asking about it.