423
STANFORD TECHNOLOGY LAW REVIEW
VOLUME 16, NUMBER 2 WINTER 2013
EMPLOYEE AND INVENTOR WITNESSES IN
PATENT TRIALS: THE BLURRY LINE BETWEEN
EXPERT AND LAY TESTIMONY
Alex Reese*
CITE AS: 16 STAN. TECH. L. REV. 423 (2013)
http://stlr.stanford.edu/pdf/witnessesinpatenttrials.pdf
ABSTRACT
Parties in patent infringement lawsuits frequently must choose a witness to
explain complex or scientific technology behind an invention or an accused
product that sits at the heart of a claim or a defense. Often, the parties select an
employee witness such as an engineer, scientist, or a named inventor of the
patent-in-suit who can testify based on first-hand experience with the technology
in question rather than a hired expert, who must prepare an expert report and
who may not share the same incentives and goals as the litigant. Because these
employee witnesses testify regarding technical or scientific issues, but they do so
from first-hand knowledge, courts have struggled over whether such witnesses
must be designated as experts under the Federal Rules of Evidence. This has
created a growing conflict among courts over how far a lay witness may go in
testifying about technical and scientific matters before crossing the boundary into
expert testimony. This Article addresses these conflicting cases and proposes an
approach that courts can use to determine which topics in patent cases are
appropriate matters only for expert witnesses and which topics may be addressed
by highly skilled and knowledgeable lay witnesses.
* Associate, Farella Braun + Martel LLP. My thanks to Jeff Fisher, Partner at Farella Braun
+ Martel, for getting me started on the research trail that led to this Article and for invaluable
feedback and assistance along the way. Thanks also to Mark Lemley, William H. Neukom
Professor of Law at Stanford Law School, for guidance, editing, and advice during the
research and writing process.
424 STANFORD TECHNOLOGY LAW REVIEW [Vol. 16:229
INTRODUCTION....................................................................................................... 424
I. EXPERT AND LAY TESTIMONY UNDER THE FEDERAL RULES OF EVIDENCE ..... 426
II. THE STRATEGIC ADVANTAGES OF OFFERING EMPLOYEES AND INVENTORS
AS LAY RATHER THAN EXPERT WITNESSES ..................................................... 429
A. Avoiding the Expert Report Requirements of Rule 26 ................................ 430
B. Protecting Documents from Discovery ...................................................... 433
C. Protecting the Attorney-Client Privilege .................................................... 435
III. HOW COURTS IN PATENT CASES HAVE DRAWN THE LINE BETWEEN LAY
AND EXPERT TESTIMONY ................................................................................. 437
A. Testimony Regarding Legal Standards ...................................................... 438
B. Lay Testimony on Prior Art ........................................................................ 440
C. Inventor Testimony Describing a Device ................................................... 442
D. Testimony Describing Accused Devices ..................................................... 444
IV. A PROPOSAL FOR HOW TO DISTINGUISH BETWEEN LAY AND EXPERT
TESTIMONY ...................................................................................................... 445
A. Scientific, Technical or Specialized Knowledge Testimony........................ 447
B. Testimony Based on Firsthand Experience Versus Testimony Gathered
for Trial ...................................................................................................... 448
C. Opinion Testimony Versus Fact Testimony ................................................ 450
CONCLUSION ................................ .......................................................................... 451
INTRODUCTION
Because patent litigation frequently involves complex scientific an d
technical issues, litigants in patent infringement suits face a key question that
can shape an entire trial: who is the best witness to explain the technology in
the case to the jury? Whether it is the patent owner trying to explain the patent-
in-suit or the accused infringer describing prior art or an accused product, the
choice of witnesses who can accomplish this important task normally comes
down to either a retained expert or an in-house employee witness (often a
scientist, engineer, or a named inventor of the patent-in-suit). The choice
between these two kinds of witnesses encompasses several smaller strategic
questions, such as which witness the jury will find most credible or likeable,
which witness knows the technology and the industry the best, and so forth. But
before reaching those issues, litigants face a surprisingly difficult threshold
question of whether the employee witness must be designated as an expert in
order to testify or whether he may testify as a lay witness.
Although many litigants and many courts have addressed this very issue,
there is no consensus, creating a growing conflict in patent suits over just how
far a lay witness may go in testifying about technical or scientific issues before
the testimony crosses the line into the expert’s realm. Explaining the
technology behind an invention or an accused product is a crucial aspect of
patent cases, and strategic considerations such as credibility with the jury, the
added expense of relying on paid experts, and the possibility that an expert may
not entirely agree with the litigant’s position have driven parties to instead
