Except as provided in this subchapter, the principles of law and equity, including the law merchant and the law relating to principal and agent, estoppel, laches, fraud, misrepresentation, duress, coercion, mistake, insolvency, or other validating or invalidating cause shall apply to actions and proceedings under this subchapter.
(Added
Section effective 180 days after Nov. 29, 1990, and applicable with respect to certain actions for debts owed the United States pending in court on that effective date, see section 3631 of