Document ID: ./input/supremecourt_opinions/opinions/13pdf/12-158_6579.pdf
Page Number: 20

Cite as:  572 U. S. ____ (2014) 

17 

Opinion of the Court 

mon  household  substances.”  Brief  for  United  States  13, 
n. 3.  That the statute would apply so broadly, however, is 
the  inescapable  conclusion  of  the  Government’s  position: 
Any  parent  would  be  guilty  of  a  serious  federal  offense—
possession  of  a  chemical  weapon—when,  exasperated  by 
the  children’s  repeated  failure  to  clean  the  goldfish  tank,
he  considers  poisoning  the  fish  with  a  few  drops  of  vine-
gar.  We  are  reluctant  to  ignore  the  ordinary  meaning  of 
“chemical  weapon”  when  doing  so  would  transform  a 
statute passed to implement the international Convention
on Chemical Weapons into one that also makes it a federal
offense  to  poison  goldfish.    That  would  not  be  a  “realistic 
assessment[ ] of congressional intent.”  Post, at 6 (SCALIA, 
J., concurring in judgment).  

In light of all of this, it is fully appropriate to apply the
background assumption that Congress normally preserves 
“the  constitutional  balance  between  the  National  Govern-
ment and the States.”  Bond I, 564 U. S., at ___ (slip op., at 
10).  That assumption is grounded in the very structure of
the Constitution.  And as we explained when this case was 
first  before  us,  maintaining  that  constitutional  balance  is
not  merely  an  end  unto  itself.    Rather,  “[b]y  denying  any 
one government complete jurisdiction over all the concerns 
of public life, federalism protects the liberty of the individ-
ual from arbitrary power.”  Ibid. 

The  Government’s  reading  of  section  229  would  “ ‘alter
sensitive federal-state relationships,’ ” convert an astonish-
ing amount of “traditionally local criminal conduct” into “a
matter for federal enforcement,” and “involve a substantial 
extension  of  federal  police  resources.”  Bass,  404  U. S.,  at 
349–350.  It  would  transform  the  statute  from  one  whose 
core concerns are acts of war, assassination, and terrorism 
into a massive federal anti-poisoning regime that reaches
the simplest of assaults.  As the Government reads section 
229,  “hardly”  a  poisoning  “in  the  land  would  fall  outside
the federal statute’s domain.”  Jones, 529 U. S., at 857.  Of