October Term 2006 · Docket 05-848
Does a physical change that raises emissions require a new permit?
Environmental groups and Duke Energy dispute how to measure pollution increases under federal air rules.
Verified source milestones
- — An official oral-argument transcript was verified.
The arguments, in order
This case may have been argued more than once. Each entry below uses that session's official transcript. Later arguments do not erase earlier ones.
Argument 1 ·
What happened at the argument
Sean Donahue argued the Clean Air Act requires a permit for any physical change that increases emissions.
Justice Scalia asked if the case is a regulatory interpretation question rather than a statutory one.
Justice Alito suggested that expert disagreement indicates the regulations are not clear on their face.
Chief Justice Roberts noted that agencies can change interpretations over time if rules are ambiguous.
Read the official transcript for this argument · Official argument details
Sources used for this argument breakdown
- Official Supreme Court Transcript — file page 10, lines 33-49 — Transcript, file page 10, lines 33-49
- Official Supreme Court Transcript — file page 12, lines 37-25 — Transcript, file page 12, lines 37-25
- Official Supreme Court Transcript — file page 25, lines 43-17 — Transcript, file page 25, lines 43-17
- Official Supreme Court Transcript — file page 3, lines 17-37 — Transcript, file page 3, lines 17-37
- Official Supreme Court Transcript — file page 3, lines 39-45 — Transcript, file page 3, lines 39-45
- Official Supreme Court Transcript — file page 3, lines 7-15 — Transcript, file page 3, lines 7-15
- Official Supreme Court Transcript — file page 4, lines 11-21 — Transcript, file page 4, lines 11-21
- Official Supreme Court Transcript — file page 5, lines 21-29 — Transcript, file page 5, lines 21-29
- Official Supreme Court Transcript — file page 5, lines 47-13 — Transcript, file page 5, lines 47-13
- Official Supreme Court Transcript — file page 6, lines 27-31 — Transcript, file page 6, lines 27-31
- Official Supreme Court Transcript — file page 6, lines 45-3 — Transcript, file page 6, lines 45-3
- Official Supreme Court Transcript — file page 7, lines 43-47 — Transcript, file page 7, lines 43-47
- Official Supreme Court Transcript — file page 8, lines 41-7 — Transcript, file page 8, lines 41-7
- Official Supreme Court Transcript — file page 8, lines 9-15 — Transcript, file page 8, lines 9-15
- Official Supreme Court Transcript — file page 9, lines 31-39 — Transcript, file page 9, lines 31-39
- Official Supreme Court Transcript — file page 9, lines 43-7 — Transcript, file page 9, lines 43-7
A citizen's guide to the whole case
What this case is about
The Clean Air Act requires owners of large pollution sources to get a permit before making changes that increase emissions. The parties disagree on how to measure those increases. Environmental Defense argues the rules require a permit for any physical change that raises output. Duke Energy argues the rules allow changes if the increase stays below a set limit.
Official sources for this section
- Official Supreme Court Transcript — file page 12, lines 37-25 — Transcript, file page 12, lines 37-25
- Official Supreme Court Transcript — file page 25, lines 43-17 — Transcript, file page 25, lines 43-17
- Official Supreme Court Transcript — file page 3, lines 17-37 — Transcript, file page 3, lines 17-37
How the case got here
The Supreme Court heard oral argument in this case on November 1, 2006.
Official sources for this section
- Official Supreme Court Transcript — file page 3, lines 7-15 — Transcript, file page 3, lines 7-15
What each side wants
Environmental Defense wants the Court to require a permit for any physical change that raises emissions.
Duke Energy wants the Court to allow changes that stay below a specific emission limit.
Official sources for this section
- Official Supreme Court Transcript — file page 12, lines 37-25 — Transcript, file page 12, lines 37-25
- Official Supreme Court Transcript — file page 25, lines 43-17 — Transcript, file page 25, lines 43-17
- Official Supreme Court Transcript — file page 3, lines 17-37 — Transcript, file page 3, lines 17-37
What each side says
Environmental Defense argues the law defines a modification as any physical change that increases pollution.
Duke Energy argues the regulations allow changes if the increase remains below a set threshold.
Official sources for this section
- Official Supreme Court Transcript — file page 12, lines 37-25 — Transcript, file page 12, lines 37-25
- Official Supreme Court Transcript — file page 25, lines 43-17 — Transcript, file page 25, lines 43-17
- Official Supreme Court Transcript — file page 3, lines 17-37 — Transcript, file page 3, lines 17-37
What the justices asked
Justice Scalia asked if agency opinions existed when the legal challenge began.
Justice Alito asked if expert disagreement shows the rules are unclear on their face.
Official sources for this section
- Official Supreme Court Transcript — file page 10, lines 33-49 — Transcript, file page 10, lines 33-49
- Official Supreme Court Transcript — file page 3, lines 39-45 — Transcript, file page 3, lines 39-45
- Official Supreme Court Transcript — file page 4, lines 11-21 — Transcript, file page 4, lines 11-21
- Official Supreme Court Transcript — file page 5, lines 21-29 — Transcript, file page 5, lines 21-29
- Official Supreme Court Transcript — file page 5, lines 47-13 — Transcript, file page 5, lines 47-13
- Official Supreme Court Transcript — file page 6, lines 27-31 — Transcript, file page 6, lines 27-31
- Official Supreme Court Transcript — file page 6, lines 45-3 — Transcript, file page 6, lines 45-3
- Official Supreme Court Transcript — file page 7, lines 43-47 — Transcript, file page 7, lines 43-47
- Official Supreme Court Transcript — file page 8, lines 41-7 — Transcript, file page 8, lines 41-7
- Official Supreme Court Transcript — file page 8, lines 9-15 — Transcript, file page 8, lines 9-15
- Official Supreme Court Transcript — file page 9, lines 31-39 — Transcript, file page 9, lines 31-39
- Official Supreme Court Transcript — file page 9, lines 43-7 — Transcript, file page 9, lines 43-7
Why it matters
This case defines when power plants must get permits for upgrades. It affects how companies manage pollution controls. It shapes the balance between environmental protection and industrial flexibility. The outcome sets a standard for measuring emission increases nationwide.
Official sources for this section
- Official Supreme Court Transcript — file page 12, lines 37-25 — Transcript, file page 12, lines 37-25
- Official Supreme Court Transcript — file page 25, lines 43-17 — Transcript, file page 25, lines 43-17
- Official Supreme Court Transcript — file page 3, lines 17-37 — Transcript, file page 3, lines 17-37
What happens next
This article currently covers the argument record. Use the official docket link for later case activity.
Official sources for this section
- Official Supreme Court Transcript — file page 10, lines 33-49 — Transcript, file page 10, lines 33-49
- Official Supreme Court Transcript — file page 3, lines 39-45 — Transcript, file page 3, lines 39-45
- Official Supreme Court Transcript — file page 3, lines 7-15 — Transcript, file page 3, lines 7-15
- Official Supreme Court Transcript — file page 4, lines 11-21 — Transcript, file page 4, lines 11-21
- Official Supreme Court Transcript — file page 5, lines 21-29 — Transcript, file page 5, lines 21-29
- Official Supreme Court Transcript — file page 5, lines 47-13 — Transcript, file page 5, lines 47-13
- Official Supreme Court Transcript — file page 6, lines 27-31 — Transcript, file page 6, lines 27-31
- Official Supreme Court Transcript — file page 6, lines 45-3 — Transcript, file page 6, lines 45-3
- Official Supreme Court Transcript — file page 7, lines 43-47 — Transcript, file page 7, lines 43-47
- Official Supreme Court Transcript — file page 8, lines 41-7 — Transcript, file page 8, lines 41-7
- Official Supreme Court Transcript — file page 8, lines 9-15 — Transcript, file page 8, lines 9-15
- Official Supreme Court Transcript — file page 9, lines 31-39 — Transcript, file page 9, lines 31-39
- Official Supreme Court Transcript — file page 9, lines 43-7 — Transcript, file page 9, lines 43-7
Official Court provenance
Official docket and case history · Official Supreme Court oral-argument detail page
Title and summary sources
- Official Supreme Court Transcript — file page 12, lines 37-25 — Transcript, file page 12, lines 37-25
- Official Supreme Court Transcript — file page 25, lines 43-17 — Transcript, file page 25, lines 43-17
- Official Supreme Court Transcript — file page 3, lines 17-37 — Transcript, file page 3, lines 17-37
- Official Supreme Court Transcript — file page 12, lines 37-25 — Transcript, file page 12, lines 37-25
- Official Supreme Court Transcript — file page 25, lines 43-17 — Transcript, file page 25, lines 43-17
- Official Supreme Court Transcript — file page 3, lines 17-37 — Transcript, file page 3, lines 17-37
Revision history
- Revision 1 · Official Transcript ·
Correction: Rewritten to the concise citizen-facing editorial standard.
- Revision 2 · Official Transcript ·
Correction: Migrated to the dated official Court activity contract without model use.