The 7th U.S. Circuit Court of Appeals reversed a 2010 ruling Thursday by a federal judge in Wisconsin's Eastern District.
Judge Rudolph Randa threw out a case involving Ernest Gibson, now 17, who suffered lead poisoning and sued a half dozen paint manufacturers. At the time, Randa said the "risk contribution theory" used in the case violated the due process rights of the defendants, which made the lead carbonate pigment.
The "risk contribution theory" was approved by the Wisconsin Supreme Court in another lead poisoning case in 2005. The theory uses state law to apportion liability based on the proportion of the market a manufacturer held when the plaintiff was injured.
Gibson's attorney, Peter Earle, said the appeals court ruling is "a complete vindication" of the 2005 decision, according to the Journal Sentinel.
The state Supreme Court in 2005 ruled Steven Thomas, a Milwaukee teenager who said he was poisoned from lead paint chips, could sue paint manufacturers, even if he did not know which one had made the product that caused his injuries.
Supporters of the ruling said it would ensure injured children could get justice from an industry when there was evidence it knew its paint was toxic. But, opponents said it created a system in which manufacturers were guilty until proven innocent.
Gov. Scott Walker and the GOP-majority Legislature approved a law in 2011 that undid the Supreme Court decision for future cases. The state budget last year included a provision aimed at blocking lead paint lawsuits that had already been filed involving 171 children, including Gibson.
Attorney Ralph Weber, who represents defendant American Cyanmid, says the counsel for all the companies had no comment on the ruling.
Gibson's case returns to federal court in Milwaukee for further proceedings.