In United States v. McKinnon, 721 F.2d 19 (1st Cir. 1983), the United States Court of Appeals for the First Circuit rejected the contention that the appellant was entitled to suppression of intercepted conversations relating to federal firearms offenses because the Massachusetts law enforcement officers who intercepted those conversations were executing a state court- issued wiretap order that authorized the interception of only conversations relating to drug offenses.
In its analysis of the "minimization" requirements found in 18 U.S.C. 2518(5), the McKinnon Court held:
We do not believe that evidence relating to crimes other than those specified in a wiretap warrant must be discovered "inadvertently" or take officers by "surprise" in order for a court properly to authorize the use of such evidence pursuant to section 2517(5). Congress intended that evidence relating to unauthorized offenses should be given retroactive judicial approval under section 2517(5) if the "original wiretap warrant was lawfully obtained, . . . was sought in good faith and not as a subterfuge search, and that the communication was in fact incidentally intercepted during the course of a lawfully executed order. (Emphasis supplied).
. . .
. . . While an interception that is unanticipated is a fortiori incidental, the converse is not true: something does not have to be unanticipated in order to be incidental. Evidence of crimes other than those authorized in a wiretap warrant are intercepted "incidentally" when they are the by-product of a bona fide investigation of crimes specified in a valid warrant. Congress did not intend that a suspect be insulated from evidence of one of his illegal activities gathered during the course of a bona fide investigation of another of his illegal activities merely because law enforcement agents are aware of his diversified criminal portfolio. (721 F.2d at 22-23.)