The Ninth Circuit wants a Delaware court to explain what it meant in a decision that seemed to cut a chink in decades of precedent blocking corporate shareholders from pursuing derivative actions after the company in which they invested is acquired.

Taking action Thursday in a long-standing appeal on behalf of institutional investors in Countrywide Financial, the U.S. Court of Appeals for the Ninth Circuit certified a question to the Supreme Court of Delaware addressing the standing requirements for derivative shareholder actions.