when to do so would not substantially burden federal policies. See, e.g., Lora v. Board of Education, 74 F.R.D. 565, 576 (E.D.N.Y.); cf. ACLU v. Flitch, 638 F.2d 1336. 1342-45 (5th Cir. Unit A Mar. 1981). F146. In their briefs, appellants suggest that the privilege they assert has an independent b