Document ID: ./input/supremecourt_opinions/opinions/22pdf/21-1449_d9eh.pdf
Page Number: 1

(Slip Opinion) 

OCTOBER  TERM,  2022 

1 

Syllabus 

NOTE:  Where  it  is  feasible,  a  syllabus  (headnote)  will  be  released,  as  is 
being  done  in  connection  with  this  case,  at  the  time  the  opinion  is  issued. 
The  syllabus  constitutes  no  part  of  the  opinion  of  the  Court  but  has  been 
prepared  by  the  Reporter  of  Decisions  for  the  convenience  of  the  reader. 
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337. 

SUPREME COURT OF THE UNITED STATES 

Syllabus 

GLACIER NORTHWEST, INC., DBA CALPORTLAND v. 
INTERNATIONAL BROTHERHOOD OF TEAMSTERS 
LOCAL UNION NO. 174 

CERTIORARI TO THE SUPREME COURT OF WASHINGTON 

No. 21–1449.  Argued January 10, 2023—Decided June 1, 2023 

Glacier  Northwest  delivers concrete to customers  in  Washington  State 
using ready-mix trucks with rotating drums that prevent the concrete 
from  hardening  during  transit.    Concrete  is  highly  perishable,  and 
even concrete in a rotating drum will eventually harden, causing sig-
nificant damage to the vehicle.  Glacier’s truck drivers are members of 
the International Brotherhood of Teamsters Local Union No. 174.  Af-
ter a collective-bargaining agreement between Glacier and the Union
expired, the Union called for a work stoppage on a morning it knew the 
company was in the midst of mixing substantial amounts of concrete, 
loading  batches  into  ready-mix  trucks,  and  making  deliveries.    The 
Union directed drivers to ignore Glacier’s instructions to finish deliv-
eries in progress.  At least 16 drivers who had already set out for de-
liveries  returned  with  fully  loaded  trucks.    By  initiating  emergency 
maneuvers to offload the concrete, Glacier prevented significant dam-
age  to  its  trucks,  but  all  the  concrete  mixed  that  day  hardened  and 
became useless. 

Glacier sued the Union for damages in state court, claiming that the 
Union  intentionally  destroyed  the  company’s  concrete  and  that  this 
conduct amounted to common-law conversion and trespass to chattels. 
The Union moved to dismiss Glacier’s tort claims on the ground that
the National Labor Relations Act (NLRA) preempted them.  While a 
federal  law  generally  preempts  state  law  when  the  two  conflict,  the 
NLRA preempts state law even when the two only arguably conflict. 
San Diego Building Trades Council v. Garmon, 359 U. S. 236, 245.  In 
the Union’s view, the NLRA—which protects employees’ rights “to self-
organization, to form, join, or assist labor organizations, . . . and to en-