Expert witnesses are primarily hired by attorneys representing plaintiffs and defendants along with insurance companies defending against environmental claims. The majority of cases involve insurance companies hiring experts to challenge lawsuits against them, though experts also support personal injury litigation for plaintiffs. Legal professionals handling complex environmental litigation need scientific credibility that determines case outcomes. Attorneys require experts who can establish causation, quantify damages, interpret regulations, and provide testimony that meets legal standards while withstanding opposing counsel challenges. Insurance companies need scientific analysis that accurately assesses liability and supports defense strategies based on sound environmental science.