provisions of law. (iii) Overturn The head of an agency may overturn a decision of the panel if, not later than 30 days after the date on which the panel issues the decision, the agency head personally exercises the authority granted by this clause to overturn such decision. (iv) Finality Each decision of a panel established under subparagraph (A) or overturned pursuant to clause (iii) of this subparagraph shall be final but subject to appeal and review under subsection (c). (D) Access to classified information The head of an agency that establishes a panel under subparagraph (A) shall afford access to classified information to the members of the panel as the head determines— (i) necessary for the panel to hear and review an appeal under this subsection