Where an administrative interpretation of a statute invokes the outer limits of Congress' power, the courts expect a clear indication that Congress intended that result. See Edward J. DeBartolo Corp. v. Florida Gulf Coast Building & Constr. Trades Council, 485 U. S. 568, 575 (1988). This requirement stems from our prudential desire not to needlessly reach constitutional issues and the assumption that Congress does not casually authorize administrative agencies to interpret a statute to push the limit of congressional authority. See ibid. This concern is heightened where the administrative interpretation alters the federal-state framework by permitting federal encroachment upon a traditional state power. See United States v. Bass, 404 U. S. 336, 349 (1971) ('[U]nless Congress conveys its purpose clearly, it will not be deemed to have significantly changed the federal-state balance'). Thus, 'where an otherwise acceptable construction of a statute would raise serious constitutional problems, the Court will construe the statute to avoid such problems unless such construction is plainly contrary to the intent of Congress.' DeBartolo, supra, at 575.