Tom Lynch Steers Legal at High Growth Speed

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In January 2025, precision diagnostics company BillionToOne announced record revenues, which more than doubled from 2023 to 2024. The news followed on the heels of a successful Series D funding round that closed with $130 million raised in May 2024.

Not bad for a company that isn’t yet a decade old.

With a growing market share, BillionToOne, whose mission is to make precision diagnostics more accurate, accessible, and actionable for all, is growing fast. As a hypergrowth company, BillionToOne requires people who are motivated to learn and open to a variety of new ideas. People like Tom Lynch.

The general counsel, chief compliance officer, and board secretary at BillionToOne is well into his legal career. The legal and business leader also has mainstay names like Novartis and Boston Scientific on his résumé. But there’s something about the emerging company, high-growth environment that keeps drawing Lynch back into the fray.

“This type of environment means a lot of growth and expansion in a short period of time,” Lynch explains. “We’ve tripled in size since I came here two and a half years ago. As the first in-house legal leader in the company, I was able to help set the foundation and principles for the function and then systematically build as the company grew.”

The GC says there is no standard playbook for building out a legal function in an emerging company. The environment and culture dictate the approach, and since there’s often very little time to study that environment, being effective means existing as a work in progress. Legal must learn to enable the business, provide counsel, and build out systems, all on the move. It’s not for the faint of heart, but it’s where Lynch excels.

As he’s built out his legal team at BillionToOne, Lynch abides by a handful of principles that may prove helpful for other legal leaders in this space.

Extreme Ownership

“Extreme ownership is an operating principle that we emphasize at BillionToOne,” Lynch says. “Your work isn’t done until the project is done. If the clinical team needs help, you help. If you need to pitch in in an area that may not be your area of expertise or core responsibilities, you pitch in. Your goal is the team’s goal, and your success is measure[d] by your ability to move the team forward and together achieve unachievable goals.

“No one on my team will ever tell you that because the ‘legal part’ of the project is done, their work is done,” he continues. “That would be unsatisfying. Our mentality allows our small legal team to take ownership, collaborate effectively, and achieve our collective goals. It is extremely fulfilling.”

Principles-Based Approach

When providing legal advice at BillionToOne, Lynch says that the team grounds its advice in principles and values. “Employees are faced with choices every day, and while the legal team will always be available to provide specific legal guidance, a member of a small legal team does not need to advise on every decision,” he says.

If employees consider internal company values, understand the legal principles behind the rules, and put the patient’s interest first, they’re going to make a good choice, he says. BillionToOne only hires the very top talent: individuals who are inquisitive, experienced, and inherently motivated to perform high quality work.

“Team members want to be the best in all areas of their work, including compliance,” Lynch says.

He tries to remember that before he arrived, his company was meeting legal requirements without him and the legal team. “They were doing a good job without us, which means we have to demonstrate value every day,” he says. He acknowledges that compliance can be simpler when the company has fifty employees, but the company now has over five hundred employees, and the GC says the stakes are higher: “There is more at risk for our employees, our customers, and the patients we serve.”

“We’re excited and proud to partner with Tom and the BillionToOne team in their pursuit of making molecular diagnostics more effective and accessible,” says Scott Nichols, partner at Nichols Weitzner Thomas LLP. “Tom truly exemplifies the leadership principles on which he’s built his legal team, and he’s positioned the company for long-term, continued success.”

Actionable Advice

Decision-makers and business leaders at BillionToOne aren’t coming to the legal team for a plethora of hypotheticals. They want guidance. Lynch says it’s incumbent upon him and the lawyers on his team to provide actionable advice for the rest of the organization. And the GC says providing that type of advice, for some, may feel uncomfortable.

“I tell new hires that you have to be comfortable operating with less resources than you were used to at a law firm or larger company,” Lynch says. “You have to become skilled at knowing when it’s OK to move ahead and when the question and the risks require you to pause and seek out more information.” He and his team don’t always need to turn over every stone; they rationally and deliberately identify which stones they need to flip, evaluate, advise, and move on.

When it needs to seek out more information, the legal team takes the time and resources to fully understand the legal risks. “We are fortunate to have outside counsel who partner with us to provide clear and thorough advice that allows the in-house team to evaluate with our business leaders what is acceptable and move forward,” Lynch says. 

It’s not about good risk tolerance versus bad risk tolerance, he adds. “It’s rationally evaluating the risks and systematically navigating the path in a complex regulatory environment to achieve the business objectives.”

Build As You Go

The nature of a high-growth company means there aren’t established procedures or processes. Legal works with the business team to build systems that are scalable over time while the business continues to hum along.

“As the first in-house legal leader in the company, I was able to help set the foundation and principles for the function and then systematically build as the company grew.”

Tom Lynch

As BillionToOne keeps growing, Lynch’s team continues to provide tools and processes to its business that increase its self-sufficiency. “We set up systems so the more common compliance decisions come naturally, and focus the team on higher-risk, more complex questions,” he explains.

The speed of the business isn’t going to slow down, but that’s exactly the speed Lynch prefers.

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