Invalidity Opinions in Patent Litigation

Shielding Against Liability, Reducing Exposure to Enhanced Damages, Attorney-Client Privilege Implications

Recording of a 90-minute premium CLE webinar with Q&A

Conducted on Thursday, November 14, 2019

Recorded event now available

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Program Materials

This CLE webinar will provide patent counsel with guidance on the use of invalidity opinions in defense of patent infringement claims. The panel will discuss the issue of waiver of the attorney-client privilege and other factors when considering invalidity opinions. The panel will provide best practices for obtaining and using invalidity opinions.


Recent decisions, including Halo Electronics Inc. v. Pulse Electronics (U.S. 2016), have changed the landscape and renewed awareness of the role an invalidity opinion can play in patent litigation. Obtaining an invalidity opinion and examining infringement risks can protect an accused infringer from a willful infringement finding and significant damages.

However, obtaining and utilizing invalidity opinions is not without its risks. The alleged infringer should consider the timing as well as the potential steps that could be triggered by an invalidity opinion. Further, a price for using an invalidity opinion could be a waiver of attorney-client privilege.

Listen as our authoritative panel of patent attorneys examines the use of invalidity opinions and the considerations counsel must address when drafting an invalidity opinion. The panel will also offer best practices for using invalidity opinions.



  1. Use of invalidity opinions
  2. Drafting invalidity opinions
    1. Key considerations
    2. Privilege implications
  3. Recent cases
  4. Best practices for obtaining and using invalidity opinions
    1. Timing
    2. Triggers
    3. Attorney-client privilege


The panel will review these and other noteworthy issues:

  • What are the benefits of obtaining invalidity opinions? What are the risks?
  • How have courts addressed invalidity defenses after Halo?
  • Under what circumstances should invalidity opinions be sought to protect from infringement claims and enhanced damages?


Cahill, Ronald
Ronald E. Cahill

Co-Chair, Intellectual Property Department
Nutter McClennen & Fish

Mr. Cahill works with clients of all sizes to solve their most challenging intellectual property problems. His advice...  |  Read More

Weisbruch, April
April E. Weisbruch

Sheppard Mullin Richter & Hampton

Ms. Weisbruch focuses on all aspects of intellectual property, including patent prosecution and patent litigation. Her...  |  Read More

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