Briefs in Support of Petitioners
Support of Respondents
Other Court Action
Tackles Global Warming
On April 2, 2007 the U. S. Supreme Court ruled 5-4 in a strongly-worded opinion that CO2 is a pollutant and that states can regulate its emissions, bolstering California’s Clean Cars Law.
Read the Union of Concerned Scientists fact sheet on implications of the Supreme Court decision.
Background on the Mass. v EPA Suit
The Supreme Court heard arguments on
whether carbon dioxide is an air pollutant and on whether the U.S.
Environmental Protection Agency can regulate global warming
The court has based its decision on two questions. First, does the Clean Air Act
give the Environmental Protection Agency the authority to regulate
greenhouse gases? And second, if it gives EPA that authority, can
EPA avoid exercising that authority simply because it doesn’t
want to? Clean Cars Campaign members believe the answers are yes,
and no, respectively. The Clean Air Act clearly states that carbon
dioxide is an air pollutant, and by refusing to regulate it as a
pollutant, the Bush administration has evaded the law.
Motor vehicles spew out almost a third of the nation’s
greenhouse gas emissions. The world’s leading scientists
overwhelmingly agree that greenhouse gases are a major contributor
to global warming, and that immediate steps are needed to prevent
The case before the high court is known as Massachusetts v. EPA,
and it stems from 2003, when the U.S. EPA and Bush administration
rejected a petition by environmentalists to regulate CO2. The U.S.
Court of Appeals for the District of Columbia Circuit upheld the
administration position in 2005 in a splintered decision. The U.S.
Supreme Court agreed last summer to take the case this session.
Massachusetts and 13 other states, along with several cities and
various environmental groups including Environmental Defense, the
Natural Resources Defense Council, Union of Concerned Scientists,
Sierra Club, U.S. Public Interest Research Group and others joined
to challenge the administration position.
The decision and its implications are significant for
In the absence of federal action on global warming pollution and
because of the threat that global warming represents to the economy
and environment, California has set its own limits on global
warming pollution from cars. Twelve other states have
adopted the California standards, and several others are
considering adopting them.
The car companies, which have backed the Bush administration in the
federal case, have
sued to invalidate the California standards. They assert
— similar to the Bush administration argument in the federal
case — that the state doesn’t have legal authority to
limit motor vehicle greenhouse gas emissions.
The Clean Cars Campaign legal argument is simple:
Download the Mass v. EPA Primer.
- Section 302(g) of the Clean Air Act defines an “air
pollutant” to include “any chemical, substance or
matter emitted into the ambient air.” CO2 and other
greenhouse gases clearly meet this definition.
- Section 202(a)(1) of the Act authorizes EPA to regulate any
pollutant emitted by motor vehicles that the agency determines
“may reasonably be anticipated to endanger public health
- In Section 302(h), Congress explicitly defined
“welfare” to include “effects on soils,
water, crops, vegetation, manmade materials, animals, wildlife,
weather, visibility, and climate.” So
threats to the “climate” are expressly included in
dangers to our “welfare.”
Briefs in Support of Petitioners
Petitioners' opening brief, filed August 31, 2006
Brief amici curiae of municipalities
Brief amici curiae of climate scientists
Brief amici curiae of Entergy Corporation
- Brief amici curiae of Calpine Corporation
Brief amici curiae of Madeleine K. Albright
Brief amici curiae of Tribal governments
Brief amici curiae State of Delaware
Brief amici curiae of religious groups
Brief amici curiae of wildlife conservation organizations and state agencies
Brief amici curiae of the states of Arizona, Iowa, Maryland, Minnesota, and Wisconsin
Brief amicus curiae of Aspen Skiing Company
Brief amici curiae of regional environmental groups
Brief amici curiae of former EPA Administrators
Brief amici curiae of ocean and conservation organizations
Petitioners reply to U.S. government and industry respondents, filed November 15, 2006
Briefs in Support of Respondents
- Respondents' opening brief
Brief amici curiae–Competitive Enterprise Institute
Brief amici curiae from Michigan and other states
Brief amici curiae from Robert Bork et. al.
Brief amici curiae from Ken Starr et.al.