Defending Against Claims Alleging Allergic Hypersensitivity

Grant W. Hollingsworth, Partner | Hollingsworth LLP

Grant W. Hollingsworth is a partner at Hollingsworth LLP who defends chemical and drug manufacturers in products liability and toxic tort litigation, pairing legal analysis with close work in the underlying scientific data. He develops case themes from detailed review of scientific data and company documents, regularly takes depositions of expert and fact witnesses, prepares witnesses for direct and cross-examination at trial, and handles summary judgment, trial, and appellate advocacy.

• Education & Credentials

Mr. Hollingsworth earned his J.D. from Georgetown Law in 2012 and his B.A. from Brown University in 2008. He is admitted to practice in the District of Columbia and Maryland, and before the U.S. Court of Appeals for the Fourth Circuit and the U.S. District Court for the District of Maryland.

• Recognition & Leadership

He has been recognized in Chambers USA and named to Super Lawyers for Personal Injury – Products Defense (2026). At the firm, he serves on the Recruitment Committee.

• Professional Involvement

His recent writing concentrates on preemption and products liability, including “Depo-Provera Plaintiffs Attempt to Escape Preemption Via Impermissible Expert Testimony” (Daily Business Review, January 2026), “What We’re Watching in 2026: Preemption Under Trump 2.0” (February 2026), and “Products Liability Claims Against Digital Platforms Ignore Arbitration Agreements” (June 2026), along with articles for Bloomberg Law and Law360 on arbitration and venue. He is a member of the National Association of Railroad Trial Counsel and attended the National Railroad Trial College.

• Experience

Mr. Hollingsworth’s matters include the Zometa pharmaceutical products liability cases and In re Tepezza Marketing, Sales Practices, and Products Liability Litigation, in which he helped secure a Rule 12(b)(6) dismissal for Horizon Therapeutics in October 2024. He has represented clients in Department of Justice and Office of Inspector General investigations and in state and federal consumer fraud matters, served as first chair in federal district court, and secured an appellate victory for a sports franchise in Naimoli v. Pro-Football, Inc., 120 F.4th 380 (4th Cir. 2024). Before becoming partner, he was the lead associate on multiple trial teams and clerked in the general counsel’s office of Norfolk Southern Corporation.

Joseph F. Altieri, Partner | Hollingsworth LLP

Joseph F. Altieri is a partner at Hollingsworth LLP who defends multimillion-dollar products liability cases, in which he has served as lead trial associate, argued pretrial and trial motions, and taken numerous depositions of plaintiffs and treating physicians. His practice centers on distilling the complexities of products liability litigation into clear, persuasive themes for judges and juries. He also has extensive experience preparing and defending corporate and expert witnesses, developing trial strategy, and managing complex pre-trial litigation in high-stakes matters.

• Education & Credentials

Mr. Altieri received his J.D., cum laude, from Georgetown Law in 2017, where he was Vice-President of the Student Bar Association and Development Editor of the Journal of Gender and the Law, and received the Alan Goldstein Memorial Award for exceptional client advocacy and a Dean’s Certificate for outstanding service to the law school community. He earned his B.B.A., magna cum laude, from the University of Miami in 2009. He is admitted in the District of Columbia and before the U.S. Supreme Court and the U.S. District Court for the District of Columbia.

• Recognition & Leadership

He has been named a Super Lawyers Rising Star for Personal Injury – Products Defense each year from 2023 through 2026. At Hollingsworth LLP, he co-chairs the firm’s LGBTQ+ employee community group and serves on its recruitment, professional development, and community engagement committees.

• Professional Involvement

Mr. Altieri is a member of the American Bar Association, the District of Columbia LGBTQ+ Bar Association, and the National LGBTQ+ Bar Association. His recent work includes a Law360 article on preparing corporate representatives for deposition under Rule 30(b)(6) (November 2025), a CLE webinar panel, “Litigating in Judicial Hellholes in 2025 and Beyond” (November 2025), and an April 2026 presentation on depositions of in-house counsel and the complex legal and ethical issues they raise.

• Experience

In major products liability matters, Mr. Altieri has supervised teams of attorneys vetting hundreds of potential experts across scientific disciplines, prepared and defended expert witnesses at deposition, prepared corporate witnesses for deposition and trial testimony, and directed large-scale discovery operations. He previously interned at the U.S. Attorney’s Office for the District of Columbia, the Federal Public Defender’s Office for the Eastern District of Virginia, and the Superior Court of the District of Columbia, and served as an assistant director of admission at the University of Miami and SUNY.

David I. Schifrin, Partner | Hollingsworth LLP

David I. Schifrin is a partner at Hollingsworth LLP who handles pharmaceutical, products liability, and toxic tort matters across the country, with a practice devoted to complex litigation. He is known for thorough factual investigation and for uniting litigation strategy with the specifics of each case. His experience includes managing complex discovery, working closely with expert witnesses, and representing clients in highstakes product liability litigation.

• Education & Credentials

Mr. Schifrin earned his J.D., cum laude, from Georgetown Law in 2017, where he was a staff editor of the Journal of National Security Law & Policy, and his B.A. in Economics, with College Honors, from Washington University in St. Louis in 2013. He is admitted to practice in the District of Columbia, Colorado, Maryland, and Montana.

• Recognition & Leadership

Mr. Schifrin has been named a Super Lawyers Rising Star for Civil Litigation Defense three years running (2024, 2025, and 2026). He is recognized for synthesizing complex facts and legal argument into a clear defense strategy and for a proven track record in pharmaceutical, products liability, and toxic tort matters, and his analysis of the defense bar’s leading issues — regulatory restrictions in mass tort litigation and the sufficiency of expert testimony — has appeared in For the Defense, Bloomberg Law, and the AmLaw Litigation Daily.

• Professional Involvement

Mr. Schifrin is a member of the American Bar Association. His publications include “Navigating Regulatory Bans and Restrictions in Mass Tort Litigation” (For the Defense, October 2025), “Sixth Circuit Tackles Insufficient Expert Testimony in Litigation” (Bloomberg Law, August 2025), and a co-authored AmLaw Litigation Daily article on litigating pesticide bans (September 2024).

• Experience

Mr. Schifrin has extensive experience preparing and defending expert witnesses at depositions and trials, helping experts present complex scientific topics in testimony a jury can follow. He manages corporate discovery issues and prepares corporate witnesses to testify in personal and representative capacities. He previously served as a law clerk to the Hon. Anthony C. Epstein of the Superior Court of the District of Columbia and as an Assistant Attorney General in the Civil Litigation Division of the Office of the Attorney General for the District of Columbia.

SESSION 1 – Why Allergic Hypersensitivity Cases Are Different: The Science a Litigator Needs, Claims, and Motions Practice | 2:30pm – 3:30pm

This session opens with why allergic hypersensitivity cases are different: roughly one third of the U.S. population has an allergy, yet the general rule is that the idiosyncratic, hypersensitive, or allergic consumer generally may not recover in a products liability case. It then covers the science a litigator needs — the four classifications of hypersensitivity, sensitizers versus irritants, dose, exposure, and route, threshold dose, ADME, biomarkers, and the tests used to diagnose allergic disease — through real-world case studies including Zurbriggen v. Twin Hill and Cartwright v. Home Depot. The session closes with the causes of action and motions practice that frame these cases: strict liability, negligence, failure to warn, design and manufacturing defect, and consumer protection claims over “hypoallergenic” labels; the principal affirmative defenses; and Rule 12 practice, including Twiqbal plausibility challenges, judicial notice of FDA materials, preemption after Riegel and Monsanto v. Durnell, and the learned intermediary doctrine.

BREAK | 3:30pm – 3:40pm

SESSION 2 – Causation, Rule 702 / Daubert Challenges, Summary Judgment, and Trial Strategy | 3:40pm – 4:40pm

This session turns to causation — where allergic hypersensitivity claims tend to break down. It works through general versus specific causation; the primary methodologies of epidemiology, dose-response, and background risk; the Bradford Hill criteria; differential diagnosis; latency; and the growing use of genetic testing under Rule 35. The session then addresses Rule 702 / Daubert admissibility challenges to expert testimony in allergic hypersensitivity cases, including the 2023 amendments to Rule 702, recent gatekeeping decisions such as the Acetaminophen MDL and its reversal in Rutledge v. Walgreen, and multiple chemical sensitivity litigation. It concludes with the summary judgment standard and representative decisions, and with trial strategy: developing a persuasive defense theme, presenting complex scientific evidence to a jury, direct and crossexamination of experts, and closing argument.