A federal judge Wednesday expressed skepticism over a proposed class action lawsuit that would seek as much as $200 billion in damages against the tobacco industry for its allegedly deceptive marketing of light cigarettes.

In a daylong hearing, Eastern District of New York Judge Jack B. Weinstein wondered how the plaintiffs could define a viable class — and accurately assess damages — when the tens of millions of people who have smoked light cigarettes might have chosen to do so for any number of reasons.