A lawyer known for battling tech giants over the treatment of workers has set her sights on International Business Machines Corp.

Shannon Liss-Riordan on Monday filed a class-action lawsuit in federal court in Manhattan on behalf of three former IBM employees who say the tech giant discriminated against them based on their age when it fired them. Liss-Riordan, a partner at Lichten & Liss-Riordan in Boston, has represented workers against Amazon, Uber, and Google and has styled her firm as the premier champion for employees left behind by powerful tech companies.

“Over the last several years, IBM has been in the process of systematically laying off older employees in order to build a younger workforce,” the former employees claim in the suit, which draws heavily on a ProPublica report published in March that said the company has fired more than 20,000 employees older than 40 in the last six years.