schwit1 writes: Prosecutors in a Los Angeles suburb say they have dramatically scaled back a vast and legally questionable eavesdropping operation, built by federal drug agents, that once accounted for nearly a fifth of all U.S. wiretaps. The wiretapping, authorized by prosecutors and a single state-court judge in Riverside County, alarmed privacy advocates and even some U.S. Justice Department lawyers, who warned that it was likely illegal. An investigation last year by The Desert Sun and USA TODAY found that the operation almost certainly violated federal wiretapping laws, while using millions of secretly intercepted calls and texts to make hundreds of arrests nationwide. Riverside's district attorney, Mike Hestrin, acknowledged being concerned by the scope of that surveillance, and said he enacted "significant" reforms last summer to rein it in. Wiretap figures his office released this week offer the first evidence that the enormous eavesdropping program has wound down to more routine levels.