IP Law Essentials

Experts in Patent Cases: Who They Are and Why to Hire Them


Experts serve important functions in patent infringement litigation. They help investigate the facts and issues surrounding each individual case, assist the judge and jury in understanding complex technical and economic issues, and assist in developing a case strategy. Usually, an expert is retained with the intent that they will provide opinions and testimony in the case, including on ultimate legal issues of the case such as whether a party infringes or whether a patent claim is invalid. Sometimes, however, non-testifying or consulting experts are retained to provide specialized case support at a fraction of the cost.

In a typical patent litigation, each party hires one or more "technical experts" to provide opinions on infringement and invalidity, and a "damages expert" to provide opinions relating to the damages in the case. These roles - and some less common patent litigation expert roles - are described below:

  • Technical Expert - These experts are hired to opine on technical issues such as the level of skill in the art at the time of invention, claim construction, invalidity, and infringement. Technical experts usually have extensive experience related to the specific technology covered by the patent or the general scientific field encompassing the patent. Note – you can save money by looking into your own organization for possible experts, whether they serve as testifying or consulting experts. If you choose to take that approach, however, the other side will likely attempt to paint the expert as biased.
  • Damages Expert - These experts are hired to testify on financial and economic issues such as the appropriate damages amount to be awarded, market demand, comparable licenses, lost profits, and reasonable royalties. Often such experts are economists, certified public accountants, or have a master's degree in business administration.

In addition to the typical experts described above, it may be beneficial or necessary to hire other experts to provide additional support in the case. For example, for the technical issues of a case, a source code expert or testing expert may provide additional analysis or opinions. Also, for the damages issues of a case, a survey expert or licensing expert might prove helpful. These types of experts are described below:

  • Source Code Expert - Source code experts may be hired to review and analyze source code related to products at issue. Source code review can be time-consuming, and hiring a source code expert can offer cost savings both because they may be hired as non-testifying experts and because they may not have as much technical expertise as a testifying expert. Source code experts usually have at least a bachelor's degree in computer science or engineering.
  • Testing Expert - Testing experts are often hired to assist technical experts in developing and supporting their opinions. For example, counsel may hire a testing expert to test whether products perform the claimed method, or to determine whether a product can be redesigned to avoid infringement.
  • Survey Expert - A survey expert may be hired to assist the testifying damages expert in understanding consumer decisions related to the accused product. For example, a survey expert may conduct a survey to determine the value of the allegedly patented feature or whether the patented feature drives the consumer demand for the accused product.
  • Licensing Expert - Licensing experts may be hired to assist the testifying damages expert in comparing licenses, valuation, and competitive analysis. Specialized licensing experts may also be brought in when the patent is a standard essential patent.


More questions? Contact the authors or visit Fish's Intellectual Property Law Essentials.

Authors: Taylor Caldwell, Joanna Fuller