In a potentially ominous development for corporations, a handful of decisions by federal judges in New York have strayed from the traditional rule that a company can’t be found to have had fraudulent intent—known in the law as scienter—unless the individual making a false or misleading material statement actually had such an intent.

Under a new theory of “collective scienter,” fraudulent intent can be imputed to the corporation by aggregating the intent of employees who had nothing to do with a false corporate statement. At its most extreme, the knowledge of a janitor who came across a discarded document in the ...