As worldwide efforts by Jewish heirs to reclaim Nazi-looted art continue to surge—a movement that some say former Manhattan District Attorney Robert Morgenthau fueled with his bold 1998 seizure of the MOMA’s “Dead City III” painting—an art-restitution lawsuit launched in Manhattan state court appears to be growing in importance.

Impassioned oral argument unfolded in the case earlier this month before a lively Appellate Division, First Department bench, with justices challenging the lawyers while often barely waiting for each other to finish, or repeating a question until a better answer was given.