The U.S. Court of Appeals for the Second Circuit signaled Thursday that it may fully address, for the first time, the question of whether a decades-old change to federal law rendered a commonly used tool for extending U.S. Securities and Exchange Commission investigations unenforceable in federal court.

At the heart of the dispute is the SEC’s use of “tolling agreements,” which allow the agency to extend the five-year statute of limitations for bringing an enforcement action. The mechanism is generally seen as beneficial to both sides of an SEC investigation, and the pacts themselves have rarely, if ever, been challenged in federal court.