Unrivaled 2025: Brian Rosenthal of Gibson Dunn

In Corrigent Corp. v. Cisco Systems Inc., you defended Cisco against a $350 million damages claim from a patent assertion entity with related companies that sued the company. After getting three of four asserted patents dismissed before trial, a Texas federal judge issued a directed verdict of non-infringement, followed by another trial where a jury rendered a verdict of non-infringement, invalidity, and prior use in January 2025. Can you tell us about your trial strategy?

As my dad always says, the only way to climb a mountain is one step at a time. What looked impossible—beating a four-patent infringement claim for hundreds of millions of dollars in Texas—became doable when we chipped away one argument at a time. Pretrial, we used surgical arguments to narrow the case to one patent for trial.

At trial, our strategy was simplicity and focus. We dropped any story that wasn’t on message, and we pounded with every witness that Cisco did not use the patent. Instead, we argued Cisco was the true innovator that developed the technology. Our focus resulted in only the third-ever directed verdict by Judge Albright (I was lucky enough to have led the team that won the first two years earlier.)

Two weeks later, we were back before Judge Albright defending Cisco in another patent trial against another plaintiff. This time our message was two-fold: We don’t use the patent, and we were first anyway. Again, simplicity and consistency of message won the day. The jury was out for an hour before returning a complete sweep verdict of non-infringement, prior use and invalidity, among the first-ever verdicts of prior commercial use under the 2013 AIA statute.

Can you describe a major hurdle that happened during the course of Corrigent. How did you overcome it?

The biggest challenge in the Corrigent trial was trying to get the jury—and the judge—to understand a very technical argument as to why Cisco does not infringe. We had to somehow get the jury to understand the difference between a “physical” port and a “virtual” port in a computer network device. Ultimately, we decided the best way to make it clear was to bring in a huge Cisco device and show the jury what we were talking about. It turns out that device became the star of the trial.

Starting with my opening through every witness examination—direct and cross— we rolled in the Cisco router and made it a constant presence. By the end of the trial, the biggest challenge turned into our best asset. If there is one thing everyone in that courtroom knew, it was the difference between a physical port and a virtual port.

When did you first know you wanted to be a trial lawyer? What clicked for you?

When I was a kid—before I got to control the TV remote—my dad would always watch Perry Mason reruns. Seeing the OG trial lawyer cross-examine witnesses into submission always impressed me. And he always won. I dreamed then that one day I would be a trial lawyer like him.

As I got older, I lost track of that dream and pursued a degree in computer science. While I loved the creativity and elegance of coding, I knew that I wanted to put my competitive side to use. So, I remembered my childhood dream of being a trial lawyer and went to law school. One hundred and twenty-five cases later, my favorite part of the job is still dismantling a witness on cross. Well, that and winning.

What are the major keys to winning over a jury or a judge?

As Einstein said, if you can’t explain it simply, you don’t understand it well enough. Finding that simple story—the one that would convince my four kids in even the most complex patent case—is the biggest challenge. It takes work. Once we find that story, we repeat it. Again, and again. And we don’t chase rabbits. We don’t pick losing fights. Credibility is king. We never misrepresent, and we always back up our promises.

What is the best advice you give young trial lawyers?

“Find your own voice. Juries are very good at detecting BS. They can spot a faker a mile away. So don’t try to be anyone else. Find yourself and then be yourself. The rest will take care of itself.”

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