In the
 United States Court of Appeals
              For the Seventh Circuit
                       ____________

No. 06-1385
UNITED STATES OF AMERICA,
                                          Plaintiff-Appellee,
                             v.

NING WEN,
                                      Defendant-Appellant.
                       ____________
         Appeal from the United States District Court
             for the Eastern District of Wisconsin.
        No. 04-CR-241—William C. Griesbach, Judge.
                       ____________
ARGUED OCTOBER 20, 2006—DECIDED DECEMBER 14, 2006—
  AMENDED ON DENIAL OF REHEARING FEBRUARY 21, 2007
                    ____________


 Before EASTERBROOK, Chief Judge, and BAUER and
EVANS, Circuit Judges.
  EASTERBROOK, Chief Judge. A jury found Ning Wen
guilty of violating the export-control laws by providing
militarily useful technology to the People’s Republic of
China without the required license. See 50 U.S.C.
§1705(b). He has been sentenced to 60 months’ imprison-
ment. His only argument on appeal is that the district
court should have suppressed evidence derived from a
wiretap approved under the Foreign Intelligence Surveil-
lance Act. After reviewing the materials in camera, the
judge concluded that the intercept order was amply
justified and denied this motion.
2                                              No. 06-1385

  As enacted in 1978, FISA applied to interceptions the
“primary purpose” of which was foreign intelligence; as
amended in 2001 by the USA PATRIOT Act, the statute
applies to interceptions that have international intelli-
gence as a “significant purpose”. 50 U.S.C. §1804(a)(7)(B).
The Foreign Intelligence Surveillance Court of Review
has concluded that the amended statute allows domestic
use of intercepted evidence as long as a “significant”
international objective is in view at the intercept’s incep-
tion. Sealed Case, 

(F.I.S. Ct. Rev. 2002). Wen
asks us to disagree with that decision and hold that
evidence gathered under FISA cannot be used in domestic
criminal investigations or prosecutions, even when the
“domestic” crime is linked to international espionage, once
that international investigation has “fizzled out” (Wen’s
phrase) and the investigation of domestic crime neces-
sarily assumes primary significance.
  The statutory question under the current version of the
Act is whether acquiring international intelligence is a
“significant purpose” of the intercept. The intercept’s
“primary” purpose may or may not be pertinent to the
fourth amendment (we discuss that subject below) but is
not pertinent to the validity of the intercept under the
statute. Like the district court, we have reviewed the
affidavits in camera and conclude that the statutory
standards for an intercept order have been satisfied. There
is no basis for suppression under FISA itself. 50 U.S.C.
§1806(e), (g).
  The fourth amendment does not supply a better footing
for exclusion. FISA requires each intercept to be authorized
by a warrant from a federal district judge. See 50 U.S.C.
§1803(a). This brings into play the rule of United States
v. Leon, 

(1984), that the exclusionary rule
must not be applied to evidence seized on the authority of
a warrant, even if the warrant turns out to be defective,
unless the affidavit supporting the warrant was false or
No. 06-1385                                               3

misleading, or probable cause was so transparently
missing that “no reasonably well trained officer [would]
rely on the warrant.” 

  At one time it was seriously questioned whether an
intercept order is a “warrant” for constitutional purposes,
see Telford Taylor, Two Studies in Constitutional Inter-
pretation 79-88 (1969), but characterization was settled
in favor of “warrant” status by Dalia v. United States, 

, 256 n.18 (1979). And our in camera review
reveals that well-trained officers were entitled to rely on
this warrant. The Executive Branch did the right thing
in asking for a warrant. Suppose that FISA were the wrong
source of authority and that the judge should have turned
the request down because the investigation’s domestic
component overshadowed its international aspect. Then
the Executive Branch could have obtained a domestic
intercept order under Title III. The evidence narrated
in the affidavit establishes probable cause to believe
that phone lines were being used to discuss or plan
violations of 50 U.S.C. §1705(b). An error about which
court should have issued a warrant, under which statute,
does not support exclusion.
  The only plausible constitutional objection to the war-
rant actually issued would be that FISA uses a definition of
“probable cause” that does not depend on whether a
domestic crime has been committed. Under 50 U.S.C.
§1805(a)(3), an order may be based on probable cause to
believe that the target is an agent of a foreign power and
that the conversations to be intercepted concern the
agent’s dealings with that foreign power; the judge need
not find probable cause to believe that the foreign agent
probably is violating the law of this nation (although this
may be implied by the findings that FISA does require).
  Yet we know from the administrative-search cases
that the “probable cause” of which the fourth amendment
4                                              No. 06-1385

speaks is not necessarily probable cause to believe that
any law is being violated. The Court held in Camara v.
Municipal Court, 

(1967), and See v. Seattle,

(1967), that municipal officials may not
barge into homes or businesses to look for violations of
the housing code; they must have warrants, which may
issue on probable cause to believe that the city has
adopted a reasonable system of inspections and is not
targeting citizens for irregular or malicious reasons.
Similarly, Marshall v. Barlow’s, Inc., 

(1978),
holds that, although federal inspectors need warrants to
inspect business premises for violations of the Occupa-
tional Safety and Health Act, these warrants may issue on
probable cause to believe that the agency is implementing
a reasonable system of inspections that includes the
business in question. Inspectors lawfully on the prem-
ises under such warrants may report any violations of
law that they find; evidence in plain view need not be
overlooked, even if that evidence concerns a different
statute.
  These principles carry over to FISA. Probable cause to
believe that a foreign agent is communicating with his
controllers outside our borders makes an interception
reasonable. If, while conducting this surveillance, agents
discover evidence of a domestic crime, they may use it to
prosecute for that offense. That the agents may have
known that they were likely to hear evidence of domestic
crime does not make the interception less reasonable
than if they were ignorant of this possibility. Justice
Stewart’s position that the plain-view doctrine is limited
to “inadvertent” discoveries, see Coolidge v. New Hamp-
shire, 

, 469-71 (1971), has not carried the day.
In Horton v. California, 

(1990), the Court
held that evidence in plain view may be seized without
a warrant even though the police expected to find it.
Likewise evidence of a domestic crime, acquired during
No. 06-1385                                              5

an intercept that is reasonable because it concerns traffic
between a foreign state and one of its agents in the United
States, may be used in a domestic prosecution whether or
not the agents expected to learn about the domestic
offense. It is enough that the intercept be adequately
justified without regard to the possibility that evidence
of domestic offenses will turn up. Interception of Wen’s
conversations was adequately justified under FISA’s terms,
so there is no constitutional obstacle to using evidence
of any domestic crimes he committed.
                                                AFFIRMED
A true Copy:
      Teste:

                       ________________________________
                       Clerk of the United States Court of
                         Appeals for the Seventh Circuit




                  USCA-02-C-0072—2-21-07