The district court's decision to abstain from deciding federal and state law claims concerning the legality of efforts by the plaintiff-town to declare beachfront properties that encroach onto public trust lands a nuisance, and regulate them accordingly, is reversed and remanded, where: 1) the circumstances of this case do not merit abstention; and 2) while the claims asserted here do involve a sensitive area of North Carolina public policy, resolving them is not sufficiently difficult or disruptive of that policy to free the district court from its "unflagging obligation to exercise its jurisdiction."