Lewis v. NL Industries, Inc., 988 N.E.2d 197

Plaintiffs Mary Lewis, Tashwan Banks, and Kathleen O’Sullivan (on behalf of themselves and others similarly situated) filed a class-action against DL Industries et al. over lead-paint exposure and testing costs.
The case descended through appellate history starting with Lewis I (2003) and Lewis II (2006), addressing whether testing costs could be damages and whether conspiracy claims could proceed.
The circuit court decertified the class on testing-cost causation; on appeal the court remanded and certified a Rule 308 question.
The certified question asked whether the Lead Poisoning Prevention Act (Act) constitutes a legally sufficient proximate cause of lead-screening costs.
The appellate court limited its review to the certified question, conducting de novo analysis of proximate causation in general, not case-specific merits.
The court answered yes: the Act can be a proximate cause of testing costs and remanded to address merits not resolved by the certification

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the Act can be a legally sufficient proximate cause of testing costs	Lewis argues the Act mandates screening, thus can cause costs	Defendants contend causation is not established or sole, and other factors may drive costs	Yes, the Act may be a proximate cause in general

Lewis v. Lead Industries Ass’n, 342 Ill. App. 3d 95 (2003) (banal discussion of causation in testing costs (cited for general causation framework))
Grundy v. Lincoln Park Zoo, 2011 IL App (1st) 102686 (2011) (de novo review on certified question)
Hudkins v. Egan, 364 Ill. App. 3d 587 (2006) (jurisdictional limits on certified-question review)
P.J.’s Concrete Pumping Service, Inc. v. Nextel West Corp., 345 Ill. App. 3d 992 (2004) (limits of appellate review in class-action context)
Moore v. Chicago Park District, 2012 IL 112788 (2012) (limits on appellate review; supervisory jurisdiction context)