Document ID: ./input/supremecourt_opinions/opinions/boundvolumes/558bv.pdf
Page Number: 440.0

Cite as: 558 U. S. 256 (2010) 

279 

Opinion of Roberts, C. J. 

372–373  (quoting  Kentucky  v.  Indiana,  281  U. S.  163,  173– 
174  (1930)).  In  applying  that  doctrine  to  motions  to  inter­
vene,  the  New  Jersey  v.  New  York  test  precludes  a  State 
from being  “judicially impeached  on matters  of policy  by its 
own  subjects,”  and  prevents  the  use  of  the  Court’s  original 
jurisdiction to air “intramural dispute[s]” that should be set­
tled  in  a  different  forum—namely,  within  the  States.  345 
U. S., at 373. 

The  New  Jersey  v.  New  York  test  is  also  “a  working  rule 
for good judicial administration.”  Ibid.  Without it, “there 
would  be  no  practical  limitation  on  the  number  of  citizens, 
as  such,  who  would  be  entitled  to  be  made  parties.”  Ibid. 
Indeed, the Court observed that allowing Philadelphia to in­
tervene  would  have  made  it  difﬁcult  to  refuse  attempts  to 
intervene by other users of water from the Delaware River, 
including  other  cities,  and  even  “[l]arge  industrial  plants.” 
Ibid.  The  New  Jersey  v.  New  York  test,  properly  applied, 
provides a much-needed limiting principle that prevents the 
expansion  of  our  original  proceedings  “to  the  dimensions  of 
ordinary  class  actions,”  ibid.,  or  “town-meeting  lawsuits,” 
id., at  376 (Jackson, J.,  dissenting).  See also Ohio  v.  Wyan­
dotte Chemicals Corp., supra, at 504; Utah v.  United States, 
394 U. S. 89, 95–96 (1969) (per curiam). 

II 

Applying  these  principles,  this  Court  has  never  granted 
a  nonsovereign  entity’s  motion  to  intervene  in  an  equitable 
apportionment  action.  The  reason  is  straightforward:  An 
interest  in  water  is  an  interest  shared  with  other  citizens, 
and  is  properly  pressed  or  defended  by  the  State.  And  a 
private entity’s interest in its particular share of the State’s 
water,  once  the  water  is  allocated  between  the  States,  is  an 
“intramural dispute” to be decided by each State on its own. 
New Jersey v.  New York, supra, at 373. 

The  interests  of  a  State’s  citizens  in  the  use  of  water  de­
rive  entirely  from  the  State’s  sovereign  interest  in  the  wa­