Matthew C. Sostrin

Matt’s primary focus is on developing legal strategies and briefing dispositive and other motions in federal and state courts around the country. Matt also has substantial experience litigating the admissibility of scientific and other expert testimony.

Matt joined Mayer Brown in 2003, leaving for a year in 2013 to clerk for the Hon. Thomas M. Durkin of the United States District Court for the Northern District of Illinois.

• Defended multinational food company against claims asserted by hundreds of plaintiffs recruited by Erin Brokovich related to solvents in area groundwater. Prevailed on summary judgment. Avila v. CNH Am. LLC (D. Neb. 2009).
• Defended former owner of wood treatment facility against claims asserted by thousands of neighboring residents alleging exposure to air emissions containing dioxins and other chemicals.
• National and trial level defense of multinational entity that manufactured and sold PFAS and PFAS-containing products, including resolving disputes involving implementation of natural resources damages settlement.
• National and trial level defense of multinational entity that sold asbestos and asbestos-containing products; secured numerous grants of summary judgment as well as a defense verdict following three-week jury trial in Cook County, Illinois.
• National and trial level defense of former diacetyl supplier in butter flavorings litigation alleging severe respiratory injuries from exposure to diacetyl fumes.
• Defended chemical manufacturer against class action alleging that the company's herbicide atrazine contaminated public water supplies.
• Represented natural gas utility in EPA enforcement action under TSCA involving PCBs in natural gas pipeline systems.
• Represented railroad in state and federal court actions filed by regulators and neighboring landowners involving solvents and diesel fuel in groundwater near former rail yards.
• Defended former owner of 14 chemical plants against CERCLA and contract claims asserted by the current owner to allocate environmental response costs.
• Defended tenant against the landlord’s CERCLA, RCRA, and state law claims involving groundwater contamination caused by prior occupant.

Commercial, Financial Services, and M&A-Related Litigation

• Obtained dismissal of multidistrict litigation comprised of 14 nationwide class actions seeking travel insurance coverage for COVID-related claims. In re Generali COVID-19 Travel Ins. Litig. (S.D.N.Y. 2021, aff’d 2d Cir. 2022).
• Successfully defended TC Energy in appraisal and fiduciary duty actions arising out of its $13 billion acquisition of Columbia Pipeline Group. In re Appraisal of Columbia Pipeline Grp., Inc. (Del. Ch. 2019), In re Columbia Pipeline Group, Inc. Merger Litig. (Del. 2025).
• Represented buyers and sellers of companies in post-closing disputes, including purchase price adjustments and representation and warranty claims.
• Defended banks and mortgage lenders and servicers against individual and class actions filed by borrowers, municipalities, and housing organizations alleging discrimination under the Fair Housing Act and other laws.
• Defended mortgage servicer against class action challenging imposition of property inspection and related fees following defaults. Prevailed on summary judgment. Stitt v. Citibank, N.A. (9th Cir. 2018).
• Defended mortgage servicer against actions filed by borrowers related to applications for loan modifications and related claims.
• Defended national and regional banks against class actions challenging overdraft and insufficient funds fees on checking accounts.
• Defended national bank against class actions challenging the processing of ACH transactions for tribal and offshore payday lenders.
• Represented national bank in post-judgment and bankruptcy proceedings to collect $43 million judgment against borrowers who fraudulently transferred assets.
• Defended founders of educational software company against litigation filed by minority shareholders that sought to enjoin $455 million sale of the company. Secured dismissal of all claims. Data Key Partners v. Permira Advisers LLC (Wis. 2014).

Pro Bono

• Principal drafter of the Police Accountability Task Force Report (2016), which recommended reforms to the Chicago Police Department and its oversight bodies.
• Briefed and argued appeal of racketeering conviction in Seventh Circuit.