Ms Diane Sullivan > Weil, Gotshal & Manges LLP > Princeton, United States > Lawyer Profile

Weil, Gotshal & Manges LLP
United States
Diane Sullivan photo




Diane Sullivan, a nationally recognized trial attorney, specializes in “first-of-kind,” “bet-the-company,” or otherwise high-profile matters that have garnered extensive media coverage across a range of practice areas and industries. She is often retained in high-stakes litigations to serve as lead trial counsel. She represents Fortune 500 companies in complex commercial, mass tort, class action, antitrust, patent, and environmental litigations in jurisdictions around the U.S. Ms. Sullivan has represented some of the biggest, most recognizable names across industries, including Johnson & Johnson, Altria, AstraZeneca, Campbell Soup Company, ESPN, ExxonMobil, General Electric, Merck, Philip Morris USA, Procter & Gamble, SAC Capital, Sanofi, Toyobo, and Walgreens.


New Jersey Bar; New York Bar; admitted to practice before several federal courts.


Fairfield University (BA, 1984); University of Pennsylvania Law School (JD, 1987).

Lawyer Rankings

United States > Dispute resolution > Product liability, mass tort and class action - defense: toxic tort

Appreciated by clients for its ‘great service and availability’, Weil, Gotshal & Manges LLP‘s ‘hardworking‘ team excels at handling high-stakes toxic tort disputes for energy, utilities, retail and pharmaceutical companies, in federal and state courts throughout the country. With a large group of lawyers with first-chair trial experience in the product liability and broader commercial litigation fields, the firm has great experience as trial and national co-ordinating counsel in big-ticket disputes, including as it relates to talcum powder litigation, water contamination and disputes related to plastics pollution. The team also regularly handles toxic tort disputes in a bankruptcy context, where it is able to draw upon expertise within the firm’s market-leading insolvency offering. New Jersey-based product liability and mass tort litigator par-excellence Diane Sullivan  co-heads the team alongside the ‘excellent’ David Singh  out of Silicon Valley. New York-based Theodore Tsekerides  is also a key figure, including in bankruptcy-related matters and is recognized as a ‘great communicator’. 

United States > Dispute resolution > Product liability, mass tort and class action - defense: consumer products (including tobacco)

(Leading lawyers)

Diane SullivanWeil, Gotshal & Manges LLP

Weil, Gotshal & Manges LLP provides a cradle-to-grave service to many global companies in relation to product-related concerns, including advice on crisis management and strategic development, as well as in the context of devising ‘innovative legal strategy’ to repel, at the earliest stage possible, potentially reputation-threatening litigation. New Jersey-based trial lawyer Diane Sullivan has had a string of high-profile successes in many first-of-kind and bellwether cases in the product liability/mass tort space, including for Johnson & Johnson in the talcum powder mass tort. Sullivan co-heads the team alongside ‘excellent and hardworking‘ Silicon Valley-based David Singh, who is noted for his aptitude at handling high-profile consumer product-related class actions. Bambo Obaro is also based out of Silicon Valley and regularly partners up with Singh on major consumer class actions, including his starring role in securing the dismissal of a significant consumer class action in New York federal court for a leading coffee and retail company. The arrival in June 2021 of versatile Washington DC-based litigators Drew Tulumello and Chantale Fiebig from Gibson, Dunn & Crutcher LLP strengthens the firm’s credentials, including in relation to food and beverages consumer product liability matters.

United States > Dispute resolution > Leading trial lawyers

(Hall of Fame)

Diane SullivanWeil, Gotshal & Manges LLP

(Leading trial lawyers)

Diane SullivanWeil, Gotshal & Manges LLP

Diane SullivanWeil, Gotshal & Manges LLP. Diane Sullivan in New York concentrates on high-value disputes and bet-the-company trials. Among her many successes is a highly favorable settlement for Giant Eagle in the first-ever federal jury trial against pharmacies in the opioid MDL which highlights her cross-practice expertise and high-profile work. Mass torts are another specialism in her varied practice. As first-chair lawyer in a mass tort trial, Diane secured the first defense verdict for Johnson & Johnson in New Jersey state court.

United States > Dispute resolution > Product liability, mass tort and class action - defense: pharmaceuticals and medical devices

(Hall of Fame)

Diane SullivanWeil, Gotshal & Manges LLP

Weil, Gotshal & Manges LLP combines broad-based product liability expertise with an overarching complex commercial litigation group, enabling it to effectively resource increasingly high-profile matters in the space. New Jersey-based Diane Sullivan is the most prominent figure in the group and by dint of her ‘exemplary trial skills‘ is regularly brought in at a late stage when a case is heading towards trial. This was recently exemplified by her representation of pharmacy retailer, Giant Eagle, as replacement lead trial counsel in a bellwether MDL opioid jury trial. Washington DC-based Chantale Fiebig was also involved in the aforementioned matter and her arrival in June 2021 from Gibson, Dunn & Crutcher LLP strengthens the firm’s offering, in light of her strong all-round advocacy skills and eclectic litigation offering.

United States > Dispute resolution > General commercial disputes

(Hall of Fame)

Diane SullivanWeil, Gotshal & Manges LLP

Weil, Gotshal & Manges LLP has a well-established commercial disputes practice which regularly takes on class actions before the Judicial Panel on Multi-District Litigation (MDL) and under various state multi-district litigation statutes, as well as class and collective actions in state and federal courts around the United States. High-stakes cases involving consumer fraud, unfair competition, alter ego liability, insurance, intellectual property and trade secrets litigation. Other areas of strength are bankruptcy litigation and cases involving alleged violations of the federal RICO or antitrust laws and state unfair practices laws. Clients include financial institutions, consumer and retail, media and entertainment, chemical, energy, and industrial companies as well as insurance, pharmaceutical and consumer goods companies and private equity funds. The New York-based David Lender co-chairs the global litigation department, while the US complex commercial litigation group is being led by Edward Soto in Miami, Gregory Silbert in New York, and new arrival Drew Tulumello who joined the Washington DC office in June 2021 together with Chantale Fiebig, both formerly at Gibson, Dunn & Crutcher LLP. Diane Sullivan  in New Jersey is a specialist in commercial, mass tort and class action cases in the life sciences, healthcare, pharmaceutical, and consumer product sectors.