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SUPREME COURT OF THE UNITED STATES
--------
No. 93-1260
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UNITED STATES, PETITIONER v.
ALFONSO LOPEZ, Jr.
on writ of certiorari to the united states court
of appeals for the fifth circuit
[April 26, 1995]

  Chief Justice Rehnquist delivered the opinion of the
Court.
  In the Gun-Free School Zones Act of 1990, Congress
made it a federal offense -for any individual knowingly
to possess a firearm at a place that the individual
knows, or has reasonable cause to believe, is a school
zone.-  18 U. S. C. 922(q)(1)(A) (1988 ed., Supp. V). 
The Act neither regulates a commercial activity nor
contains a requirement that the possession be connected
in any way to interstate commerce.  We hold that the
Act exceeds the authority of Congress -[t]o regulate
Commerce . . . among the several States . . . .- U. S.
Const., Art. I, 8, cl. 3.
  On March 10, 1992, respondent, who was then a 12th-
grade student, arrived at Edison High School in San
Antonio, Texas, carrying a concealed .38 caliber handgun
and five bullets.  Acting upon an anonymous tip, school
authorities confronted respondent, who admitted that he
was carrying the weapon.  He was arrested and charged
under Texas law with firearm possession on school
premises.  See Tex. Penal Code Ann. 46.03(a)(1) (Supp.
1994).  The next day, the state charges were dismissed
after federal agents charged respondent by complaint
with violating the Gun-Free School Zones Act of 1990. 
18 U. S. C. 922(q)(1)(A) (1988 ed., Supp. V).  
  A federal grand jury indicted respondent on one count
of knowing possession of a firearm at a school zone, in
violation of 922(q).  Respondent moved to dismiss his
federal indictment on the ground that 922(q) -is
unconstitutional as it is beyond the power of Congress
to legislate control over our public schools.-  The District
Court denied the motion, concluding that 922(q) -is a
constitutional exercise of Congress' well-defined power to
regulate activities in and affecting commerce, and the
`business' of elementary, middle and high schools . . .
affects interstate commerce.-  App. to Pet. for Cert. 55a. 
Respondent waived his right to a jury trial.  The
District Court conducted a bench trial, found him guilty
of violating 922(q), and sentenced him to six months'
imprisonment and two years' supervised release.  
  On appeal, respondent challenged his conviction based
on his claim that 922(q) exceeded Congress' power to
legislate under the Commerce Clause.  The Court of
Appeals for the Fifth Circuit agreed and reversed
respondent's conviction.  It held that, in light of what it
characterized as insufficient congressional findings and
legislative history, -section 922(q), in the full reach of its
terms, is invalid as beyond the power of Congress under
the Commerce Clause.-  2 F. 3d 1342, 1367-1368 (1993). 
Because of the importance of the issue, we granted
certiorari, 511 U. S. ___ (1994), and we now affirm.
  We start with first principles.  The Constitution
creates a Federal Government of enumerated powers. 
See  U. S. Const., Art. I, 8.  As James Madison wrote,
-[t]he powers delegated by the proposed Constitution to
the federal government are few and defined.  Those
which are to remain in the State governments are
numerous and indefinite.-  The Federalist No. 45, pp.
292-293 (C. Rossiter ed. 1961).  This constitutionally
mandated division of authority -was adopted by the
Framers to ensure protection of our fundamental liber-
ties.-  Gregory v. Ashcroft, 501 U. S. 452, 458 (1991)
(internal quotation marks omitted).  -Just as the
separation and independence of the coordinate branches
of the Federal Government serves to prevent the
accumulation of excessive power in any one branch, a
healthy balance of power between the States and the
Federal Government will reduce the risk of tyranny and
abuse from either front.-  Ibid.
  The Constitution delegates to Congress the power -[t]o
regulate Commerce with foreign Nations, and among the
several States, and with the Indian Tribes.-  U. S.
Const., Art. I, 8, cl. 3.  The Court, through Chief
Justice Marshall, first defined the nature of Congress'
commerce power in Gibbons v. Ogden, 9 Wheat. 1,
189-190 (1824):
-Commerce, undoubtedly, is traffic, but it is some-
thing more: it is intercourse.  It describes the
commercial intercourse between nations, and parts
of nations, in all its branches, and is regulated by
prescribing rules for carrying on that intercourse.-
The commerce power -is the power to regulate; that is,
to prescribe the rule by which commerce is to be
governed.  This power, like all others vested in Con-
gress, is complete in itself, may be exercised to its
utmost extent, and acknowledges no limitations, other
than are prescribed in the constitution.-  Id., at 196. 
The Gibbons Court, however, acknowledged that limita-
tions on the commerce power are inherent in the very
language of the Commerce Clause.  
      -It is not intended to say that these words com-
prehend that commerce, which is completely inter-
nal, which is carried on between man and man in a
State, or between different parts of the same State,
and which does not extend to or affect other States. 
Such a power would be inconvenient, and is cer-
tainly unnecessary. 
      -Comprehensive as the word `among' is, it may
very properly be restricted to that commerce which
concerns more States than one. . . .  The enumera-
tion presupposes something not enumerated; and
that something, if we regard the language or the
subject of the sentence, must be the exclusively
internal commerce of a State.-  Id., at 194-195.
  For nearly a century thereafter, the Court's Commerce
Clause decisions dealt but rarely with the extent of
Congress' power, and almost entirely with the Commerce
Clause as a limit on state legislation that discriminated
against interstate commerce.  See, e.g., Veazie v. Moor,
14 How. 568, 573-575 (1853) (upholding a state-created
steamboat monopoly because it involved regulation of
wholly internal commerce); Kidd v. Pearson, 128 U. S.
1, 17, 20-22 (1888) (upholding a state prohibition on the
manufacture of intoxicating liquor because the commerce
power -does not comprehend the purely domestic
commerce of a State which is carried on between man
and man within a State or between different parts of
the same State-); see also L. Tribe, American Constitu-
tional Law 306 (2d ed. 1988).  Under this line of
precedent, the Court held that certain categories of
activity such as -production,- -manufacturing,- and
-mining- were within the province of state governments,
and thus were beyond the power of Congress under the
Commerce Clause.  See Wickard v. Filburn, 317 U. S.
111, 121 (1942) (describing development of Commerce
Clause jurisprudence).      
  In 1887, Congress enacted the Interstate Commerce
Act, 24 Stat. 379, and in 1890, Congress enacted the
Sherman Antitrust Act, 26 Stat. 209, as amended, 15
U. S. C. 1 et seq.  These laws ushered in a new era of
federal regulation under the commerce power.  When
cases involving these laws first reached this Court, we
imported from our negative Commerce Clause cases the
approach that Congress could not regulate activities such
as -production,- -manufacturing,- and -mining.-  See,
e.g., United States v. E. C. Knight Co., 156 U. S. 1, 12
(1895) (-Commerce succeeds to manufacture, and is not
part of it-); Carter v. Carter Coal Co., 298 U. S. 238,
304 (1936) (-Mining brings the subject matter of com-
merce into existence.  Commerce disposes of it-).  Simul-
taneously, however, the Court held that, where the
interstate and intrastate aspects of commerce were so
mingled together that full regulation of interstate
commerce required incidental regulation of intrastate
commerce, the Commerce Clause authorized such
regulation.  See, e.g., Houston, E. & W. T. R. Co. v.
United States, 234 U. S. 342 (1914) (Shreveport Rate
Cases).
  In A. L. A. Schecter Poultry Corp. v. United States,
295 U. S. 495, 550 (1935), the Court struck down
regulations that fixed the hours and wages of individuals
employed by an intrastate business because the activity
being regulated related to interstate commerce only
indirectly.  In doing so, the Court characterized the
distinction between direct and indirect effects of intra-
state transactions upon interstate commerce as -a
fundamental one, essential to the maintenance of our
constitutional system.-  Id., at 548.  Activities that
affected interstate commerce directly were within
Congress' power; activities that affected interstate
commerce indirectly were beyond Congress' reach.  Id.,
at 546.  The justification for this formal distinction was
rooted in the fear that otherwise -there would be
virtually no limit to the federal power and for all
practical purposes we should have a completely central-
ized government.-  Id., at 548.  
  Two years later, in the watershed case of NLRB v.
Jones & Laughlin Steel Corp., 301 U. S. 1 (1937), the
Court upheld the National Labor Relations Act against
a Commerce Clause challenge, and in the process,
departed from the distinction between -direct- and
-indirect- effects on interstate commerce.  Id., at 36-38
(-The question [of the scope of Congress' power] is
necessarily one of degree-).  The Court held that
intrastate activities that -have such a close and substan-
tial relation to interstate commerce that their control is
essential or appropriate to protect that commerce from
burdens and obstructions- are within Congress' power to
regulate.  Id., at 37.  
  In United States v. Darby, 312 U. S. 100 (1941), the
Court upheld the Fair Labor Standards Act, stating: 
-The power of Congress over interstate commerce is
not confined to the regulation of commerce among
the states.  It extends to those activities intrastate
which so affect interstate commerce or the exercise
of the power of Congress over it as to make regula-
tion of them appropriate means to the attainment of
a legitimate end, the exercise of the granted power
of Congress to regulate interstate commerce.-  Id.,
at 118.
See also United States v. Wrightwood Dairy Co., 315
U. S. 110, 119 (1942) (the commerce power -extends to
those intrastate activities which in a substantial way
interfere with or obstruct the exercise of the granted
power-).  
  In Wickard v. Filburn, the Court upheld the applica-
tion of amendments to the Agricultural Adjustment Act
of 1938 to the production and consumption of home-
grown wheat.  317 U. S., at 128-129.  The Wickard
Court explicitly rejected earlier distinctions between
direct and indirect effects on interstate commerce,
stating:
-[E]ven if appellee's activity be local and though it
may not be regarded as commerce, it may still,
whatever its nature, be reached by Congress if it
exerts a substantial economic effect on interstate
commerce, and this irrespective of whether such
effect is what might at some earlier time have been
defined as `direct' or `indirect.'-  Id., at 125.
The Wickard Court emphasized that although Filburn's
own contribution to the demand for wheat may have
been trivial by itself, that was not -enough to remove
him from the scope of federal regulation where, as here,
his contribution, taken together with that of many
others similarly situated, is far from trivial.-  Id., at
127-128.
  Jones & Laughlin Steel, Darby, and Wickard ushered
in an era of Commerce Clause jurisprudence that greatly
expanded the previously defined authority of Congress
under that Clause.  In part, this was a recognition of
the great changes that had occurred in the way business
was carried on in this country.  Enterprises that had
once been local or at most regional in nature had
become national in scope.  But the doctrinal change also
reflected a view that earlier Commerce Clause cases
artificially had constrained the authority of Congress to
regulate interstate commerce.
  But even these modern-era precedents which have
expanded congressional power under the Commerce
Clause confirm that this power is subject to outer limits. 
In Jones & Laughlin Steel, the Court warned that the
scope of the interstate commerce power -must be
considered in the light of our dual system of government
and may not be extended so as to embrace effects upon
interstate commerce so indirect and remote that to
embrace them, in view of our complex society, would
effectually obliterate the distinction between what is
national and what is local and create a completely
centralized government.-  301 U. S., at 37; see also
Darby, supra, at 119-120 (Congress may regulate
intrastate activity that has a -substantial effect- on
interstate commerce); Wickard, supra, at 125 (Congress
may regulate activity that -exerts a substantial economic
effect on interstate commerce-).  Since that time, the
Court has heeded that warning and undertaken to
decide whether a rational basis existed for concluding
that a regulated activity sufficiently affected interstate
commerce.  See, e.g., Hodel v. Virginia Surface Mining
& Reclamation Assn., Inc., 452 U. S. 264, 276-280
(1981); Perez v. United States, 402 U. S. 146, 155-156
(1971); Katzenbach v. McClung, 379 U. S. 294, 299-301
(1964); Heart of Atlanta Motel, Inc. v. United States, 379
U. S. 241, 252-253 (1964). 
  Similarly, in Maryland v. Wirtz, 392 U. S. 183 (1968),
the Court reaffirmed that -the power to regulate com-
merce, though broad indeed, has limits- that -[t]he Court
has ample power- to enforce.  Id., at 196, overruled on
other grounds, National League of Cities v. Usery, 426
U. S. 833 (1976), overruled by Garcia v. San Antonio
Metropolitan Transit Authority, 469 U. S. 528 (1985).  In
response to the dissent's warnings that the Court was
powerless to enforce the limitations on Congress'
commerce powers because -[a]ll activities affecting
commerce, even in the minutest degree, [Wickard], may
be regulated and controlled by Congress,- 392 U. S., at
204 (Douglas, J., dissenting), the Wirtz Court replied
that the dissent had misread precedent as -[n]either
here nor in Wickard has the Court declared that
Congress may use a relatively trivial impact on com-
merce as an excuse for broad general regulation of state
or private activities,- id., at 197, n. 27.  Rather, -[t]he
Court has said only that where a general regulatory
statute bears a substantial relation to commerce, the de
minimis character of individual instances arising under
that statute is of no consequence.- Ibid. (first emphasis
added).
  Consistent with this structure, we have identified
three broad categories of activity that Congress may
regulate under its commerce power.  Perez v. United
States, supra, at 150; see also Hodel v. Virginia Surface
Mining & Reclamation Assn., supra, at 276-277.  First,
Congress may regulate the use of the channels of
interstate commerce.  See, e.g., Darby, 312 U. S., at 114;
Heart of Atlanta Motel, supra, at 256 (-`[T]he authority
of Congress to keep the channels of interstate commerce
free from immoral and injurious uses has been fre-
quently sustained, and is no longer open to question.'- 
(quoting Caminetti v. United States, 242 U. S. 470, 491
(1917)).  Second, Congress is empowered to regulate and
protect the instrumentalities of interstate commerce, or
persons or things in interstate commerce, even though
the threat may come only from intrastate activities. 
See, e.g., Shreveport Rate Cases, 234 U. S. 342 (1914);
Southern R. Co. v. United States, 222 U. S. 20 (1911)
(upholding amendments to Safety Appliance Act as
applied to vehicles used in intrastate commerce); Perez,
supra, at 150 (-[F]or example, the destruction of an
aircraft (18 U. S. C. 32), or . . . thefts from interstate
shipments (18 U. S. C. 659)-).  Finally, Congress'
commerce authority includes the power to regulate those
activities having a substantial relation to interstate
commerce, Jones & Laughlin Steel, 301 U. S., at 37, i.e.,
those activities that substantially affect interstate
commerce.  Wirtz, supra, at 196, n. 27.  
  Within this final category, admittedly, our case law
has not been clear whether an activity must -affect- or
-substantially affect- interstate commerce in order to be
within Congress' power to regulate it under the Com-
merce Clause.  Compare Preseault v. ICC, 494 U. S. 1,
17 (1990), with Wirtz, supra, at 196, n. 27 (the Court
has never declared that -Congress may use a relatively
trivial impact on commerce as an excuse for broad
general regulation of state or private activities-).  We
conclude, consistent with the great weight of our case
law, that the proper test requires an analysis of whether
the regulated activity -substantially affects- interstate
commerce.  
  We now turn to consider the power of Congress, in the
light of this framework, to enact 922(q).  The first two
categories of authority may be quickly disposed of:
922(q) is not a regulation of the use of the channels of
interstate commerce, nor is it an attempt to prohibit the
interstate transportation of a commodity through the
channels of commerce; nor can 922(q) be justified as a
regulation by which Congress has sought to protect an
instrumentality of interstate commerce or a thing in
interstate commerce.  Thus, if 922(q) is to be sustained,
it must be under the third category as a regulation
of an activity that substantially affects interstate
commerce.  
  First, we have upheld a wide variety of congressional
Acts regulating intrastate economic activity where we
have concluded that the activity substantially affected
interstate commerce.  Examples include the regulation
of intrastate coal mining; Hodel, supra, intrastate
extortionate credit transactions, Perez, supra, restaurants
utilizing substantial interstate supplies, McClung, supra,
inns and hotels catering to interstate guests, Heart of
Atlanta Motel, supra, and production and consumption
of home-grown wheat, Wickard v. Filburn, 317 U. S. 111
(1942).  These examples are by no means exhaustive,
but the pattern is clear.  Where economic activity
substantially affects interstate commerce, legislation
regulating that activity will be sustained.  
  Even Wickard, which is perhaps the most far reaching
example of Commerce Clause authority over intrastate
activity, involved economic activity in a way that the
possession of a gun in a school zone does not.  Roscoe
Filburn operated a small farm in Ohio, on which, in the
year involved, he raised 23 acres of wheat.  It was his
practice to sow winter wheat in the fall, and after
harvesting it in July to sell a portion of the crop, to feed
part of it to poultry and livestock on the farm, to use
some in making flour for home consumption, and to keep
the remainder for seeding future crops.  The Secretary
of Agriculture assessed a penalty against him under the
Agricultural Adjustment Act of 1938 because he har-
vested about 12 acres more wheat than his allotment
under the Act permitted.  The Act was designed to
regulate the volume of wheat moving in interstate and
foreign commerce in order to avoid surpluses and
shortages, and concomitant fluctuation in wheat prices,
which had previously obtained.  The Court said, in an
opinion sustaining the application of the Act to Filburn's
activity:
-One of the primary purposes of the Act in question
was to increase the market price of wheat and to
that end to limit the volume thereof that could
affect the market.  It can hardly be denied that a
factor of such volume and variability as home-
consumed wheat would have a substantial influence
on price and market conditions.  This may arise
because being in marketable condition such wheat
overhangs the market and, if induced by rising
prices, tends to flow into the market and check price
increases.  But if we assume that it is never mar-
keted, it supplies a need of the man who grew it
which would otherwise be reflected by purchases in
the open market.  Home-grown wheat in this sense
competes with wheat in commerce.-  317 U. S., at
128.
  Section 922(q) is a criminal statute that by its terms
has nothing to do with -commerce- or any sort of
economic enterprise, however broadly one might define
those terms.  Section 922(q) is not an essential part of
a larger regulation of economic activity, in which the
regulatory scheme could be undercut unless the intra-
state activity were regulated.  It cannot, therefore, be
sustained under our cases upholding regulations of
activities that arise out of or are connected with a
commercial transaction, which viewed in the aggregate,
substantially affects interstate commerce.  
  Second, 922(q) contains no jurisdictional element
which would ensure, through case-by-case inquiry, that
the firearm possession in question affects interstate
commerce.  For example, in United States v. Bass, 404
U. S. 336 (1971), the Court interpreted former 18
U. S. C. 1202(a), which made it a crime for a felon to
-receiv[e], posses[s], or transpor[t] in commerce or
affecting commerce . . . any firearm.-  404 U. S., at 337. 
The Court interpreted the possession component of
1202(a) to require an additional nexus to interstate
commerce both because the statute was ambiguous and
because -unless Congress conveys its purpose clearly, it
will not be deemed to have significantly changed the
federal-state balance.-  Id., at 349.  The Bass Court set
aside the conviction because although the Government
had demonstrated that Bass had possessed a firearm, it
had failed -to show the requisite nexus with interstate
commerce.-  Id., at 347.  The Court thus interpreted the
statute to reserve the constitutional question whether
Congress could regulate, without more, the -mere
possession- of firearms.  See id., at 339, n. 4; see also
United States v. Five Gambling Devices, 346 U. S. 441,
448 (1953) (plurality opinion) (-The principle is old and
deeply imbedded in our jurisprudence that this Court
will construe a statute in a manner that requires
decision of serious constitutional questions only if the
statutory language leaves no reasonable alternative-). 
Unlike the statute in Bass, 922(q) has no express
jurisdictional element which might limit its reach to a
discrete set of firearm possessions that additionally have
an explicit connection with or effect on interstate
commerce.  
  Although as part of our independent evaluation of
constitutionality under the Commerce Clause we of
course consider legislative findings, and indeed even
congressional committee findings, regarding effect on
interstate commerce, see, e.g., Preseault v. ICC, 494
U. S. 1, 17 (1990), the Government concedes that
-[n]either the statute nor its legislative history contain[s]
express congressional findings regarding the effects upon
interstate commerce of gun possession in a school zone.- 
Brief for United States 5-6.  We agree with the Govern-
ment that Congress normally is not required to make
formal findings as to the substantial burdens that an
activity has on interstate commerce.  See McClung, 379
U. S., at 304; see also Perez, 402 U. S., at 156 (-Con-
gress need [not] make particularized findings in order to
legislate-).  But to the extent that congressional findings
would enable us to evaluate the legislative judgment
that the activity in question substantially affected
interstate commerce, even though no such substantial
effect was visible to the naked eye, they are lacking
here.  
  The Government argues that Congress has accumu-
lated institutional expertise regarding the regulation of
firearms through previous enactments.  Cf. Fullilove v.
Klutznick, 448 U. S. 448, 503 (1980) (Powell, J., concur-
ring).  We agree, however, with the Fifth Circuit that
importation of previous findings to justify 922(q) is
especially inappropriate here because the -prior federal
enactments or Congressional findings [do not] speak to
the subject matter of section 922(q) or its relationship to
interstate commerce.  Indeed, section 922(q) plows
thoroughly new ground and represents a sharp break
with the long-standing pattern of federal firearms
legislation.-  2 F. 3d, at 1366.  
  The Government's essential contention, in fine, is that
we may determine here that 922(q) is valid because
possession of a firearm in a local school zone does
indeed substantially affect interstate commerce.  Brief
for United States 17.  The Government argues that
possession of a firearm in a school zone may result in
violent crime and that violent crime can be expected to
affect the functioning of the national economy in two
ways.  First, the costs of violent crime are substantial,
and, through the mechanism of insurance, those costs
are spread throughout the population.  See United States
v. Evans, 928 F. 2d 858, 862 (CA9 1991).  Second,
violent crime reduces the willingness of individuals to
travel to areas within the country that are perceived to
be unsafe.  Cf. Heart of Atlanta Motel, 379 U. S., at 253. 
The Government also argues that the presence of guns
in schools poses a substantial threat to the educational
process by threatening the learning environment.  A
handicapped educational process, in turn, will result in
a less productive citizenry.  That, in turn, would have
an adverse effect on the Nation's economic well-being. 
As a result, the Government argues that Congress could
rationally have concluded that 922(q) substantially
affects interstate commerce.  
  We pause to consider the implications of the
Government's arguments.  The Government admits,
under its -costs of crime- reasoning, that Congress could
regulate not only all violent crime, but all activities that
might lead to violent crime, regardless of how tenuously
they relate to interstate commerce.  See Tr. of Oral Arg.
8-9.  Similarly, under the Government's -national
productivity- reasoning, Congress could regulate any
activity that it found was related to the economic
productivity of individual citizens: family law (including
marriage, divorce, and child custody), for example. 
Under the theories that the Government presents in
support of 922(q), it is difficult to perceive any limita-
tion on federal power, even in areas such as criminal
law enforcement or education where States historically
have been sovereign.  Thus, if we were to accept the
Government's arguments, we are hard-pressed to posit
any activity by an individual that Congress is without
power to regulate.
  Although Justice Breyer argues that acceptance of
the Government's rationales would not authorize a
general federal police power, he is unable to identify any
activity that the States may regulate but Congress may
not.  Justice Breyer posits that there might be some
limitations on Congress' commerce power such as family
law or certain aspects of education.  Post, at 10-11. 
These suggested limitations, when viewed in light of the
dissent's expansive analysis, are devoid of substance.  
  Justice Breyer focuses, for the most part, on the
threat that firearm possession in and near schools poses
to the educational process and the potential economic
consequences flowing from that threat.  Post, at 5-9. 
Specifically, the dissent reasons that (1) gun-related
violence is a serious problem; (2) that problem, in turn,
has an adverse effect on classroom learning; and (3) that
adverse effect on classroom learning, in turn, represents
a substantial threat to trade and commerce.  Post, at 9. 
This analysis would be equally applicable, if not more
so, to subjects such as family law and direct regulation
of education.
  For instance, if Congress can, pursuant to its Com-
merce Clause power, regulate activities that adversely
affect the learning environment, then, a fortiori, it also
can regulate the educational process directly.  Congress
could determine that a school's curriculum has a
-significant- effect on the extent of classroom learning. 
As a result, Congress could mandate a federal curricu-
lum for local elementary and secondary schools because
what is taught in local schools has a significant -effect
on classroom learning,- cf. post, at 9, and that, in turn,
has a substantial effect on interstate commerce.
  Justice Breyer rejects our reading of precedent and
argues that -Congress . . . could rationally conclude that
schools fall on the commercial side of the line.-  Post, at
16.  Again, Justice Breyer's rationale lacks any real
limits because, depending on the level of generality, any
activity can be looked upon as commercial.  Under the
dissent's rationale, Congress could just as easily look at
child rearing as -fall[ing] on the commercial side of the
line- because it provides a -valuable service-namely, to
equip [children] with the skills they need to survive in
life and, more specifically, in the workplace.-  Ibid.  We
do not doubt that Congress has authority under the
Commerce Clause to regulate numerous commercial
activities that substantially affect interstate commerce
and also affect the educational process.  That authority,
though broad, does not include the authority to regulate
each and every aspect of local schools.  
  Admittedly, a determination whether an intrastate
activity is commercial or noncommercial may in some
cases result in legal uncertainty.  But, so long as
Congress' authority is limited to those powers enumer-
ated in the Constitution, and so long as those enu-
merated powers are interpreted as having judicially
enforceable outer limits, congressional legislation under
the Commerce Clause always will engender -legal un-
certainty.-  Post, at 17.  As Chief Justice Marshall
stated in McCulloch v. Maryland, 4 Wheat. 316 (1819):
-The [federal] government is acknowledged by all to
be one of enumerated powers.  The principle, that it
can exercise only the powers granted to it . . . is
now universally admitted.  But the question respect-
ing the extent of the powers actually granted, is
perpetually arising, and will probably continue to
arise, as long as our system shall exist.-  Id., at
405.
See also Gibbons v. Ogden, 9 Wheat., at 195 (-The
enumeration presupposes something not enumerated-). 
The Constitution mandates this uncertainty by withhold-
ing from Congress a plenary police power that would
authorize enactment of every type of legislation.  See
U. S. Const., Art. I, 8.  Congress has operated within
this framework of legal uncertainty ever since this
Court determined that it was the judiciary's duty -to
say what the law is.-  Marbury v. Madison, 1 Cranch.
137, 177 (1803) (Marshall, C. J.).  Any possible benefit
from eliminating this -legal uncertainty- would be at
the expense of the Constitution's system of enumerated
powers.  
  In Jones & Laughlin Steel, 301 U. S., at 37, we held
that the question of congressional power under the
Commerce Clause -is necessarily one of degree.-  To the
same effect is the concurring opinion of Justice Cardozo
in Schecter Poultry:
-There is a view of causation that would obliterate
the distinction of what is national and what is local
in the activities of commerce.  Motion at the outer
rim is communicated perceptibly, though minutely,
to recording instruments at the center.  A society
such as ours `is an elastic medium which transmits
all tremors throughout its territory; the only ques-
tion is of their size.'-  295 U. S., at 554 (quoting
United States v. A.L.A. Schecter Poultry Corp, 76
F. 2d 617, 624 (CA2 1935) (L. Hand, J.,
concurring)).
  These are not precise formulations, and in the nature
of things they cannot be.  But we think they point the
way to a correct decision of this case.  The possession of
a gun in a local school zone is in no sense an economic
activity that might, through repetition elsewhere, sub-
stantially affect any sort of interstate commerce.  Re-
spondent was a local student at a local school; there is
no indication that he had recently moved in interstate
commerce, and there is no requirement that his posses-
sion of the firearm have any concrete tie to interstate
commerce.  
  To uphold the Government's contentions here, we
would have to pile inference upon inference in a manner
that would bid fair to convert congressional authority
under the Commerce Clause to a general police power of
the sort retained by the States.  Admittedly, some of
our prior cases have taken long steps down that road,
giving great deference to congressional action.  See
supra, at 8.  The broad language in these opinions has
suggested the possibility of additional expansion, but we
decline here to proceed any further.  To do so would
require us to conclude that the Constitution's enumera-
tion of powers does not presuppose something not enu-
merated, cf. Gibbons v. Ogden, supra, at 195, and that
there never will be a distinction between what is truly
national and what is truly local, cf. Jones & Laughlin
Steel, supra, at 30.  This we are unwilling to do.
  For the foregoing reasons the judgment of the Court of
Appeals is

Affirmed.


