What is the test for a wiretap under section 2518(3)(c) of the Wiretap Act?

Section 2518(3)(c) requires the judge to determine, before a wiretap is authorized, that "normal investigative procedures" have been tried and have failed, or that such procedures appear unlikely to succeed if tried or are too dangerous. The district judge has discretion when determining the necessity of a wiretap. See United States v. Brone, 792 F.2d 1504 (9th Cir.1986). The affidavit must "set out a factual background that shows that ordinary investigative procedures, employed in good faith, would likely be ineffective in the particular case." Id. at 1506. Failure to satisfy the necessity requirement can result in suppression. United States v. Ippolito, 774 F.2d 1482 (9th Cir.1985).