Mary Hannon (JD ’21) did not leave science behind when she went to law school—she found a different way to use it. 

Now a managing associate at Sidley Austin LLP, Hannon has built an early legal career that spans patent law, litigation and federal clerkships. Originally a chemist, her path has been shaped by a willingness to test new roles, develop new skills, and say yes to opportunities for growth before the next step felt certain. 

One of the most important lessons she offers law students is the same one that has guided her own career: “putting yourself out there, not being afraid to try new things, and saying yes to opportunities that challenge you.” 

Hannon came to law school after earning both her undergraduate and graduate degrees in chemistry from DePaul University and working for several years in the field. She loved science, but not necessarily the lab. 

During that time, she also taught organic and general chemistry as an adjunct professor at DePaul, explaining complex scientific ideas to undergraduate students. 

Before fully committing to law school, Hannon joined Marshall, Gerstein & Borun LLP as a technical specialist, and later, a patent agent, to gain real-world experience in patent law and see whether legal practice was the right fit.  

The experience helped confirm her decision, and she continued working there through much of law school. Patent law, she realized, “would be a great way for me to use my love of both science and teaching.” 

While in law school, Hannon deepened her connection to the field she would explore further in Professor Joshua Sarnoff’s Advanced Concepts in Patent Law seminar. For the class, Hannon wrote a scholarly article about an issue she found both personally and professionally important: the lack of women in patent law and the strict eligibility requirements for the patent bar. 

Encouraged by Sarnoff, she pursued publication of the piece. 

Her article, “The Patent Bar Gender Gap: Expanding the Eligibility Requirements to Foster Inclusion and Innovation in the U.S. Patent System,” was ultimately featured on the Social Science Research Network (SSRN), covered by Law360, published in the peer-reviewed academic journal, IP Theory, and cited by U.S. senators in a letter to the U.S. Patent and Trademark Office. 

For Hannon, the article became an early example of how legal research could enter a broader professional conversation. It also reinforced the value of putting in the work before knowing exactly where that work might lead. 

After law school, Hannon continued to seek work that would stretch her. She moved from patent prosecution work at Marshall Gerstein to Sidley Austin’s litigation practice, expanding the types of legal problems she handled. 

Soon after, she clerked for Judge John Z. Lee of the U.S. Court of Appeals for the Seventh Circuit and Judge Alan D. Lourie of the U.S. Court of Appeals for the Federal Circuit. Her Seventh Circuit clerkship took her outside intellectual property law into areas such as business law, criminal law and habeas corpus proceedings. Her Federal Circuit clerkship exposed her to patent matters, including district court patent infringement cases. 

Hannon returned to Sidley after three years as a federal clerk. Since then, her practice has centered on patent litigation and appeals, along with False Claims Act and trade secret matters—often involving emerging technologies and the life sciences—as well as pro bono work. 

Together, these experiences have helped Hannon better understand what kind of lawyer she wants to become. In the future, she hopes to increase her focus on appellate practice, drawing on what she learned during her clerkships. Though, she acknowledged, “I’ve only been back at Sidley for less than a year, so I’m still trying to figure out how to translate what I learned clerking to firm life.”  

For students, Hannon’s advice is practical: explore and stay open to opportunities that may not look like an obvious fit at first. Looking back, she sees each step, from chemistry to patent law, from patent prosecution work to litigation, and then to federal clerkships, as part of a broader process that opened new doors and helped her understand what she could do and what she wanted to do. 

If students take anything from her journey, she hopes that they learn to “work hard, make time for yourself and don’t be afraid to say yes.” 

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