IN THE UNITED STATES COURT OF APPEALS

FOR THE FIFTH CIRCUIT

No. 13-20243

UNITED STATES OF AMERICA,

Plaintiff-Appellee

v.

TRANSOCEAN DEEPWATER DRILLING, INCORPORATED,

Defendant-Appellant

Appeal from the United States District Court

for the Southern District of Texas

Before REAVLEY, JONES, and GRAVES, Circuit Judges.

REAVLEY, Circuit Judge:

Transocean Deepwater Drilling, Inc. appeals from the district court’s 

order enforcing administrative subpoenas issued by the Chemical Safety and 

Hazard Investigation Board in connection with an investigation following the 

disaster on the Deepwater Horizon drilling unit in the Gulf of Mexico. 

Transocean contends that the subpoenas should have been quashed because 

the Board lacks authority to investigate the incident. We AFFIRM the district 

court’s judgment.

I.

On April 20, 2010, a blowout, explosion, and fire occurred during drilling 

operations at the Macondo lease site in the Gulf of Mexico. The Macondo well 

was being drilled by the Deepwater Horizon, a mobile offshore drilling unit

United States Court of Appeals

Fifth Circuit

FILED

September 18, 2014

Lyle W. Cayce

Clerk

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No. 13-20243

(“MODU”) tasked to the job by Transocean. As a result of the incident, eleven 

people were tragically killed, a large volume of flammable gas, oil, and other 

hazardous substances were released into the water and ambient air, and 

substantial property damage occurred.

Numerous governmental agencies responded to the disaster, including 

the Chemical Safety and Hazard Investigation Board (“CSB” or “the Board”). 

Established by the Clean Air Act Amendments of 1990 and modeled after the 

National Transportation Safety Board (“NTSB”), the CSB serves a public 

safety mission by investigating accidental releases of hazardous substances 

into the ambient air and by reporting to the public its findings and 

recommendations for preventing and minimizing the risk of industrial 

chemical accidents.

As part of its investigation into the incident at the Macondo well, the 

CSB issued five administrative subpoenas to Transocean. The subpoenas 

sought answers to interrogatories and the production of relevant records, 

including documents generated by Transocean’s own internal investigation. 

Transocean took the position that the CSB lacked authority to investigate the 

incident, and it therefore failed to comply fully with the CSB’s subpoenas.

The United States filed a petition on behalf of the CSB to enforce the 

administrative subpoenas, while Transocean moved to quash them and to 

dismiss the petition. Transocean argued that the CSB was not authorized to 

conduct an investigation because, inter alia, the incident was a marine oil spill 

over which the CSB lacks jurisdiction, and the incident did not occur on a 

stationary source.

The district court denied Transocean’s motion and ordered enforcement 

of the subpoenas. The district court held that the CSB was investigating only 

the release of airborne gases from the blowout and explosion and was not 

investigating the subsequent oil spill from the well. The court further 

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determined that the CSB would lack authority to investigate an incident 

involving a marine oil spill only if the NTSB was authorized to investigate. 

The court held that the NTSB was not authorized to investigate this incident, 

however, because the incident was located fifty miles off the coast of the United 

States on the Outer Continental Shelf and did not involve a “vessel of the 

United States,” and because the incident was not transportation related. The 

court also concluded that the Deepwater Horizon and its subsea riser comprised 

a drilling installation that satisfied the statutory requirement of a “stationary 

source” from which the accidental release of gases the CSB was authorized to 

investigate. The district court therefore held that the CSB had authority to 

investigate the incident and to issue the administrative subpoenas. 

Transocean now appeals.

II.

Administrative subpoenas issued in aid of an investigation will generally 

be enforced judicially if “(1) the subpoena is within the statutory authority of 

the agency; (2) the information sought is reasonably relevant to the inquiry; 

and (3) the demand is not unreasonably broad or burdensome.” See Burlington 

N. R. Co. v. Office of Inspector Gen., R.R. Ret. Bd., 983 F.2d 631, 638 (5th Cir. 

1993); see also United States v. Powell, 379 U.S. 48, 57-58, 85 S. Ct. 248, 255 

(1964) (holding that enforcement of administrative subpoenas requires a 

showing “that the investigation will be conducted pursuant to a legitimate 

purpose, that the inquiry may be relevant to the purpose, that the information 

sought is not already within the [agency’s] possession, and that the 

administrative steps required by [statute] have been followed”). The 

Government bears the initial burden to show that these criteria have been met, 

although the burden to make a prima facie case is “minimal.” United States v. 

Tex. Heart Inst., 755 F.2d 469, 474 (5th Cir. 1985), overruled on other grounds 

by United States v. Barrett, 837 F.2d 1341 (5th Cir. 1988) (en banc). Once the 

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Government has made a prima facie case, the burden of going forward shifts 

to the party opposing the subpoenas. Id.

In this case, Transocean focuses its arguments on appeal on the 

authority of the CSB to issue the subpoenas. We review the district court’s 

factual findings underlying its decision on this issue for clear error and its 

conclusions of law de novo. Burlington, 983 F.2d at 638, 641.

III.

Transocean contends that the CSB had no authority to issue the 

administrative subpoenas because the CSB lacked jurisdiction to investigate 

the incident at the Macondo well. An administrative agency’s authority is 

necessarily derived from the statute it administers and may not be exercised 

in a manner that is inconsistent with the administrative structure that 

Congress has enacted. See FDA v. Brown & Williamson Tobacco Corp., 529 

U.S. 120, 125, 120 S. Ct. 1291, 1297 (2000); see also Texas v. United States, 497 

F.3d 491, 500-01 (5th Cir. 2007). Here, as noted above, the CSB is an 

independent federal investigative agency established by the Clean Air Act 

Amendments of 1990. See Pub. L. No. 101-549, Title III, sec. 301, 104 Stat. 

2399 (Nov. 15, 1990). The Board is authorized to “investigate (or cause to be 

investigated), determine and report to the public in writing the facts, 

conditions, and circumstances and the cause or probable cause of any 

accidental release resulting in a fatality, serious injury or substantial property 

damages.” 42 U.S.C. § 7412(r)(6)(C)(i). An “accidental release” is “an 

unanticipated emission of a regulated substance or other extremely hazardous 

substance into the ambient air from a stationary source.” § 7412(r)(2)(A). A 

“stationary source” is defined as “any buildings, structures, equipment, 

installations or substance emitting stationary activities (i) which belong to the 

same industrial group, (ii) which are located on one or more contiguous 

properties, (iii) which are under the control of the same person (or persons 

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under common control), and (iv) from which an accidental release may occur.” 

§ 7412(r)(2)(C).

A.

Transocean argues first that the CSB lacked jurisdiction to investigate 

the incident at the Macondo well because the Deepwater Horizon is not a 

“stationary source” as that term is contemplated by the statute. Transocean 

reasons that because the word “stationary” in the term “stationary source” is 

not defined, the word must be construed as commonly understood, which 

Transocean contends means a fixed and unchanging object rather than 

something that is moveable. Transocean argues that the Deepwater Horizon

was not only moveable but also was a “vessel in navigation.” It reasons, 

therefore, that the drilling unit could not be a stationary source. We disagree 

with Transocean’s reasoning.

Transocean is correct that similar mobile offshore drilling units and 

other structures, and even the Deepwater Horizon itself, have been held to be 

vessels under maritime law. See, e.g., Demette v. Falcon Drilling Co., 280 F.3d 

492, 498-99 (5th Cir. 2002), overruled in part on other grounds by Grand Isle 

Shipyard, Inc. v. Seacor Marine, LLC, 589 F.3d 778 (5th Cir. 2009) (en banc). 

For example, in Demette, we noted that “special-purpose moveable drilling rigs, 

including jack-up rigs, are vessels within the meaning of admiralty law.” 

Demette, 280 F.3d at 498 n.18. It is also well-established that “special-purpose 

structures” may remain vessels under the Jones Act while engaged in drilling 

operations. See, e.g., Offshore Co. v. Robison, 266 F.2d 769, 776 (5th Cir. 1959). 

And under Supreme Court precedent a “watercraft practically capable of 

maritime transportation” is considered to be a “vessel” under the Longshore 

and Harbor Workers’ Compensation Act regardless of its purpose or state of 

transit at a particular moment. Stewart v. Dutra Constr. Co., 543 U.S. 481, 

497, 125 S. Ct. 1118, 1129 (2005). Indeed, the Supreme Court held that a 

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watercraft does not “pass in and out of Jones Act coverage depending on 

whether it was moving at the time of the accident.” Id. at 495-96, 125 S. Ct. at 

1128. Based on the foregoing authority, the district court in the multi-district 

litigation spawned from the Macondo well incident held that the Deepwater 

Horizon was a vessel under general maritime law. See In re Oil Spill by the 

Oil Rig “DEEPWATER HORIZON” in the Gulf of Mexico, on April 20, 2010, 

808 F. Supp. 2d 943, 950 (E.D. La. 2011); see also In re Deepwater Horizon, 745 

F.3d 157, 164 (5th Cir. 2014) (noting the vessel status of the drilling unit).

Nevertheless, in this case we are not dealing with the application of, or 

definitions under, the Jones Act and general maritime law. The fact that the 

Deepwater Horizon may be a vessel for purposes of maritime law does not 

answer the question whether it meets the specific statutory definition of a 

“stationary source” under the Clean Air Act.

The phrase “stationary source” is expressly defined by the Clean Air Act. 

When Congress provides a specific definition of a term, we must accept that 

meaning and limit our analysis to the prescribed definition. See Stenberg v. 

Carhart, 530 U.S. 914, 942, 120 S. Ct. 2597, 2615 (2000) (“When a statute 

includes an explicit definition, we must follow that definition, even if it varies 

from that term’s ordinary meaning.”); cf. Hamilton v. United Healthcare of La., 

Inc., 310 F.3d 385, 391 (5th Cir. 2002) (“A fundamental canon of statutory 

construction instructs that in the absence of a statutory definition, we give 

terms their ordinary meaning.” (emphasis added)); see also United States v. 

Crittenden, 372 F.3d 706, 711 (5th Cir. 2004) (Dennis, J., concurring in part 

and dissenting in part) (“[W]hen context dictates that a term has a particular 

definition, that definition will apply instead of the plain meaning of the term.”). 

We therefore must apply the definition of “stationary source” provided within 

§ 7412(r)(2)(C).

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We find nothing within the definition of “stationary source” found in

§ 7412(r)(2)(C) that precludes a vessel from satisfying the statutory 

requirements for a stationary source. Indeed, counsel for Transocean conceded 

during oral argument that a vessel could be stationary, but he argued that the 

drilling unit here was in constant motion over the well because of the unit’s 

stabilizing thrusters. The amicus makes the same argument, contending that 

under Coast Guard regulations the Deepwater Horizon was a vessel considered 

to be underway.

Of course, the whole point of the stabilizing thrusters is to keep the 

drilling unit largely stationary over the well so that it can perform its drilling 

operation, a “stationary activity.” See § 7412r(2)(c). Regardless whether the 

unit is considered to be underway, the Deepwater Horizon was “dynamicallypositioned” and “employed a satellite global positioning device and complex 

thruster technology to stabilize itself.” In re Oil Spill by the Oil Rig 

“DEEPWATER HORIZON” in the Gulf of Mexico, on April 20, 2010, 808 F. 

Supp. 2d 943, 950 (E.D. La. 2011) (emphasis added). Its eight directional 

thrusters were used to keep the rig in place over the wellhead during drilling. 

National Commission on the BP Deepwater Horizon Oil Spill and Offshore 

Drilling, Macondo: The Gulf Oil Disaster, Chief Counsel’s Report 29 (2011), 

available at http://www.eoearth.org/files/164401_164500/164423/full.pdf

(hereinafter “Chief Counsel’s Report”). 

It is true that the Deepwater Horizon was capable of propulsion. 

However, this propulsion ability is an advancement in drilling technology that 

has allowed these units to arrive and remain at different drilling locations,

making it easier for the oil and gas industry to drill for oil in deeper water. See

Chief Counsel’s report at 12. This is because “[i]n water depths greater than 

about 1,000 feet, it is increasingly impractical to conduct production operations 

from structures that are supported by the ocean floor, and floating facilities 

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and subsea production systems dominate.” Id. at 7. This economic advantage 

to the oil and gas industry does not mean, however, that the activity of the 

mobile drilling units cannot come under the CSB’s jurisdiction as a stationary 

source if other statutory conditions are met, even though the drilling unit is 

also a vessel. “Once moved onto location, a [dynamically positioned] rig holds 

itself in place above a drilling location using satellite positioning technology 

and directional thrusters.” Id. at 12-13; see also id. at 26 (“Dynamically 

positioned MODUs utilize dynamic satellite positioning technology connected 

to powerful directional thrusters to maintain themselves in place over a subsea 

wellhead.”). In this case, the Deepwater Horizon was deployed to the Macondo 

well site in February 2010 and had remained in place at the site for 

approximately two months.1 See id.

1 The amicus urges that the Deepwater Horizon could not be a stationary source 

because under Coast Guard regulations it is considered to be a vessel “underway” and not 

“on location.” It posits that if a vessel is not “on location” it cannot also be a “stationary 

source.” In support of this argument the amicus relies on a Coast Guard investigation report 

of the Deepwater Horizon incident that discussed the status of the drilling unit. See U.S. 

Coast Guard, Report of Investigation into the Circumstances Surrounding the Explosion, Fire, 

Sinking, and Loss of Eleven Crew Members Aboard the MOBILE OFFSHORE DRILLING 

UNIT DEEPWATER HORIZON in the Gulf of Mexico April 20–22, 2010, at I-10, available at 

https://www.hsdl.org/?view&did=6700 (hereinafter “Coast Guard Report”). The terms “on 

location” and “underway” have specific statutory definitions, however, that do not affect 

whether the vessel may be a “stationary source” for purposes of the Clean Air Act. For 

example, “on location” means merely that the drilling unit is anchored. See 46 C.F.R. § 10.107 

(“On location means that a mobile offshore drilling unit is bottom bearing or moored with 

anchors placed in the drilling configuration.”). Because the Deepwater Horizon was a 

dynamically positioned, anchor-less MODU, it could not satisfy the regulatory definition of 

“on location” and was therefore considered to be “underway.” See Coast Guard Report at I-5. 

The Coast Guard Report notes that whether a vessel is “on location” or “underway” 

determines the navigation rules that the vessel must follow, such as for minimum manning 

and operational requirements. See id. at I-5. That status alone does not indicate whether 

the vessel is a “stationary source” because a vessel may be “underway” but not “making way.” 

Id. at I-5-6. The Coast Guard Report specifically recognizes that even though a vessel does 

not meet the statutory definition for being “on location,” it may nevertheless be “essentially 

maintaining a fixed position” through the use of its dynamic positioning system. Id. at I-6. 

That was the case with the Deepwater Horizon.

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The Government urges, and the district court essentially found, that the 

Macondo drilling installation as a whole was a stationary source. We agree. 

At the time of the blowout and explosion the drilling operations occurred at a 

fixed, specific point in the Gulf of Mexico—the Macondo lease site—and the 

Deepwater Horizon was physically connected (though not anchored) at that site

and maintained a fixed position. The drilling installation as a whole included 

the drilling unit, along with its casing, wellhead, riser, and related apparatus. 

The blowout preventer alone was more than five stories tall and weighed more 

than 300 tons sitting atop the wellhead on the ocean floor. Chief Counsel’s 

Report at 29-30. The Deepwater Horizon was then connected to the wellhead 

by 5000 feet of drill pipe. See In re Oil Spill by the Oil Rig “DEEPWATER 

HORIZON,” 808 F. Supp. 2d at 950. As noted above, a stationary source

includes “any buildings, structures, equipment, installations or substance 

emitting stationary activities.” § 7412(r)(2)(C) (emphasis added). The drilling 

installation here satisfied this definition.2

Transocean raises a question in its reply brief about the terms of the 

stationary source definition, namely that the source “belong to the same 

industrial group,” be “located on one or more contiguous properties,” be “under 

the control of the same person,” and be something “from which an accidental 

release may occur.” § 7412(r)(2)(C). Transocean has never, in the district 

court, or its initial brief, raised this argument. Because we do not consider 

arguments raised for the first time in a reply brief, we decline to address this 

issue. See DePree v. Saunders, 588 F.3d 282, 290 (5th Cir. 2009).

2 Again, that the drilling unit itself was capable of propulsion and could and did use 

its thrusters to counter-act wave activity in order to remain in place over the well does not 

negate the fact that the drilling operation of the Deepwater Horizon was, at the very least, a 

“stationary activity.” See § 7412(r)(2)(C).

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B.

Transocean next argues that the CSB lacked jurisdiction to investigate 

the Macondo well incident because Congress specifically denied the CSB 

authority over this type of incident. Its argument is essentially two-fold: first, 

it contends that the Macondo well incident was a marine oil spill, and the Clean 

Air Act specifically precludes the CSB from investigating all marine oil spills; 

second, it contends that even if the statute does not preclude the CSB from 

investigating all marine oil spills, the CSB could not investigate this incident 

because the NTSB had jurisdiction to investigate.

Transocean’s argument is based on the following provision of the Clean 

Air Act:

The Board shall coordinate its activities with investigations and 

studies conducted by other agencies of the United States having a 

responsibility to protect public health and safety. The Board shall 

enter into a memorandum of understanding with the National 

Transportation Safety Board to assure coordination of functions 

and to limit duplication of activities which shall designate the 

National Transportation Safety Board as the lead agency for the 

investigation of releases which are transportation related. The 

Board shall not be authorized to investigate marine oil spills, which 

the National Transportation Safety Board is authorized to 

investigate. The Board shall enter into a memorandum of 

understanding with the Occupational Safety and Health 

Administration so as to limit duplication of activities. In no event 

shall the Board forego an investigation where an accidental release 

causes a fatality or serious injury among the general public, or had 

the potential to cause substantial property damage or a number of 

deaths or injuries among the general public.

§ 7412(r)(6)(E) (emphasis added).

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Transocean argues that the above italicized language shows that the 

CSB is not authorized to investigate marine oil spills and that, instead, the 

NTSB is authorized to investigate all of those incidents.3

The district court held that the marine oil spill exclusion did not apply 

to the CSB’s investigation of the Macondo well incident because the CSB was 

not investigating the marine oil spill associated with the disaster but rather 

was investigating the release of gases and the explosion that preceded the 

release of oil. We agree with the district court’s conclusion. 4

Although Transocean argues that the primary environmental disaster 

resulting from the Macondo well incident was the massive oil spill, it also 

concedes in its brief that the blowout, explosion, and fire, followed by the 

collapse of the Deepwater Horizon, involved the release of airborne gases. That 

release was the triggering of the CSB’s authority to investigate. See

§ 7412(r)(2)(A) (authorizing CSB investigations of accidental releases, which 

are defined as “unanticipated emissions[s] . . . into the ambient air”). 

Transocean argues, however, that because the CSB’s jurisdiction always 

depends on a release of gases, the marine oil spill exclusion (1) necessarily 

3 Transocean refers to the emphasized language as the “marine oil spill exclusion.” 

For ease of reference we use the same terminology. We also refer to the clause beginning 

with the word “which” as the “comma-which” clause.

4 The Coast Guard Report found as follows:

As the well control incident unfolded, an uncontrolled volume of gas 

flowed up from the wellhead to the MODU and onto the Drill Floor and Main 

Deck. Gas samples collected by Woods Hole Oceanographic Institute on July 

27, 2010 show that the composition of the uncontrolled gas discharged from 

the well was primarily methane (69.9%), with lesser amounts of ethane (6.9%) 

and propane (4.5%). The remainder of the gas consisted of a mixture of various 

weight hydrocarbons. Several minutes after the start of the release of gas from 

the wellhead, a gas cloud within the flammable range formed over large areas 

on several decks. The explosions likely occurred when gas from this cloud 

encountered one or more ignition sources on the Drill Floor or elsewhere on the 

MODU.

Coast Guard Report, 5-6.

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contemplates an accidental release that would otherwise be within the CSB’s 

jurisdiction but is merely incidental to a marine event, and (2) expressly 

excludes that event from CSB’s investigatory authority. A contrary conclusion, 

Transocean argues, would render the marine oil spill exclusion surplusage. 

Transocean’s argument assumes, however, that the CSB may not investigate 

any release of gases associated with a marine oil spill. As we explain, we 

disagree.

Transocean’s argument is textual, and it is primarily based on the 

statutory provision noted above that the CSB “shall not be authorized to 

investigate marine oil spills, which the National Transportation Safety Board 

is authorized to investigate.” See § 7412(r)(6)(E). According to Transocean’s 

reading of that sentence, the statute precludes the CSB from investigating all

marine oil spills insofar as the NTSB has jurisdiction over those occurrences.

We agree with the district court, however, that the CSB is not precluded 

from investigating all marine oil spills, but rather only those “spills, which” the 

NTSB may investigate. In other words, the CSB may be precluded from 

investigating those marine-related incidents that the NTSB is authorized to

investigate. This interpretation of the statute reads “which” to mean “that,”

and it comports with the statutory scheme as a whole.

Transocean contends, however, that based on the rules of grammar and 

punctuation the word “which” preceded by a comma creates a nonrestrictive,

descriptive clause so that the declarative portion of the sentence in 

§ 7412(r)(6)(E)—precluding investigation of marine oil spills—is controlling. 

See, e.g., William Strunk, Jr. & E.B. White, The Elements of Style 3-4 (3d ed. 

1979) (hereinafter “Strunk & White”) (explaining that nonrestrictive clauses 

introduced by “which” add nonessential parenthetic information and are set off 

by commas). If we were reading the sentence in isolation we might agree. But 

while the rules of grammar are not irrelevant, we should not “be guided by a 

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single sentence or member of a sentence;” rather, we must “look to the 

provisions of the whole law, and to its object and policy.” U.S. Nat’l Bank of 

Oregon v. Indep. Ins. Agents of Am., Inc., 508 U.S. 439, 455, 113 S. Ct. 2173, 

2182 (1993) (internal quotation marks and citation omitted); cf. United States 

v. Flora, 362 U.S. 145, 149, 80 S. Ct. 630, 633 (1960) (noting that a court “does 

not review congressional enactments as a panel of grammarians”).

We note first that reading the comma-which clause to mean “that” is 

consistent with subsection (E) as a whole and the subsection’s other uses of the 

word “which.” In addition to the comma-which, the statute twice uses the word 

“which” in the previous sentence, reading thusly: “The Board shall enter into 

a memorandum of understanding with the National Transportation Safety 

Board to assure coordination of functions and to limit duplication of activities 

which shall designate the National Transportation Safety Board as the lead 

agency for the investigation of releases which are transportation related.” 

§ 7412(r)(6)(E) (emphasis added). The first “which” in this sentence refers to 

the “memorandum of understanding” while the second “which” refers to 

“releases.” It is clear that each “which” in this sentence should be read as 

“that” because the clauses are restrictive, i.e. they give essential meaning 

about the preceding nouns (the “memorandum of understanding” and the 

“releases”). Although Congress is presumed to know the rules of grammar, see 

United States v. Goldenberg, 168 U.S. 102-03, 18 S. Ct. 3, 4 (1897), this 

grammatical oversight is understandable, as “[u]sing which for that is perhaps 

the most common blunder with these words.” Bryan A. Garner, Garner’s 

Dictionary of Legal Usage 889 (3d ed. 2011); see also Strunk & White at 59 

(“The use of which for that is common in written and spoken language.”).

If we read the first two uses of “which” in subsection (E) to mean “that,” 

it would be natural to construe the comma-which to also mean “that.” See

Powerex Corp. v. Reliant Energy Servs., Inc., 551 U.S. 224, 232, 127 S. Ct. 2411, 

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2417 (2007) (“[I]dentical words and phrases within the same statute should 

normally be given the same meaning.”); see also U.S. Nat’l Bank of Oregon, 508 

U.S. at 460, 113 S. Ct. at 2185. Of course, the difference between the first two 

uses of the word “which” in subsection (E) and the comma-which clause is the 

presence of the comma, and in isolation the comma could be significant. But

“a purported plain-meaning analysis based only on punctuation is necessarily 

incomplete and runs the risk of distorting a statute’s true meaning.” Id. at 

454, 113 S. Ct. at 2182; see Costanzo v. Tillinghast, 287 U.S. 341, 344, 53 S. Ct. 

152, 153 (1932) (“It has often been said that punctuation is not decisive of the 

construction of a statute.”). Construing the words in context, as we must, we 

strive to “interpret the statute ‘as a symmetrical and coherent regulatory 

scheme.’” Brown & Williamson Tobacco Corp., 529 U.S. at 133, 120 S. Ct. at 

1301 (citation omitted). Here, we must consider the “comma-which” clause 

along with the entire provision as part of “‘a holistic endeavor.’” U.S. Nat’l 

Bank of Oregon, 508 U.S. at 455, 113 S. Ct. at 2182 (citation omitted). We will 

“‘disregard the punctuation, or repunctuate, if need be, to render the true 

meaning of the statute.’” Id. at 462, 113 S. Ct. at 2186 (citation omitted).

Subsection (E) contemplates that the CSB is not the only government 

agency charged with a public safety mission and may not be the only 

investigating agency; indeed, it expressly directs the CSB to “coordinate its 

activities with investigations and studies by other agencies” with responsibility 

to protect public health and safety. § 7412(r)(6)(E). Even more specifically, 

the statute directs the CSB to “enter into a memorandum of understanding” 

with the NTSB in order to coordinate activities, limit duplication of efforts, and 

designate the NTSB as the lead agency if an accidental release is 

transportation related. Id. We agree with the district court that this provision 

must mean there is a category of marine oil spills that are non-transportation 

related and over which the NTSB lacks exclusive authority. If the comma14

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which clause of the marine oil spill exclusion simply precluded the CSB from 

investigating all marine oil spill incidents there would be no need for the 

requirement that CSB coordinate with the NTSB or other government agencies

to avoid duplication of efforts. In context, the structure of the statute, 

including the prior uses of the word “which,” indicates an intent that the 

comma-which clause was not meant to be non-restrictive.

Moreover, the statute expressly directs the CSB to investigate any time

an accidental release causes a fatality or serious injury to the general public. 

See id. (“In no event shall the Board forego an investigation where an accidental 

release causes a fatality or serious injury among the general public, or had the 

potential to cause substantial property damage or a number of deaths or 

injuries among the general public.” (emphasis added)). This must mean that 

for especially serious incidents involving either grave injury or the risk of 

injury, including marine oil spills, the CSB could have concurrent investigative 

authority with other agencies.5 And again, the CSB would be required to 

coordinate its efforts with any other agencies. This provision adds further 

support to the conclusion that the marine oil spill exclusion is not the allencompassing prohibition that Transocean urges.

We believe that looking at the full text of the statute, rather than one 

isolated clause, along with the statute’s structure and its public safety purpose 

shows that the comma-which clause was not intended to preclude the CSB from 

investigating all incidents involving marine oil spills. See U.S. Nat’l Bank of 

5 Transocean argues that this provision of subsection (E) is inapplicable here because 

the Macondo well incident was incapable of causing death or injury to members of the general 

public insofar as the disaster occurred fifty miles off the coast of the United States. First, 

this argument is inapposite to whether the CSB is precluded from investigating all marine 

oil spills in the first place. Second, the offshore location of the disaster does not preclude the 

potential for injury to persons on shore since it cannot be denied that airborne hazardous 

substances could migrate and cause injury on land.

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Oregon, 508 U.S. at 455, 113 S. Ct. at 2182 (eschewing isolated words or 

sentences in favor of “a statute’s full text, language as well as punctuation, 

structure, and subject matter”). This reading of the statute best comports with 

the overall regulatory scheme. See Brown & Williamson Tobacco Corp., 529 

U.S. at 133, 120 S. Ct. at 1301; see also U.S. Nat’l Bank of Oregon, 508 U.S. at 

461 n.10, 113 S. Ct. at 2186 n.10 (searching for “the best reading of the Act, 

despite the punctuation marks”). We conclude, therefore, that the statute did 

not categorically preclude the CSB from investigating all incidents that happen 

to include a marine oil spill.

Transocean contends that even if the CSB could otherwise investigate 

the incident at the Macondo well, it was precluded from doing so in this case 

because the NTSB was authorized to investigate. Transocean relies solely on 

49 U.S.C. § 1131(a)(1)(F), which grants the NTSB authority to investigate,

inter alia, “catastrophic” accidents that are “related to the transportation of 

individuals or property.” It asserts that the Macondo well incident was 

catastrophic and that the disaster was related to transportation because the 

Deepwater Horizon was a vessel in navigation.

However, when the blowout occurred on April 20, 2010, the Deepwater 

Horizon was dynamically positioned and physically attached to the seabed, 

having been on site and engaged in drilling operations for a number of months. 

The district court held that this fact was crucial to the determination that the 

incident was not transportation related. Transocean cites no contrary 

authority. Merely because a disaster involves a vessel does not mean that the 

disaster was necessarily related to transportation. Although the drilling unit 

may have been capable of transportation, it was not involved in transporting 

either individuals or property at the time of the blowout, explosion, and fire. 

See § 1131(a)(1)(F). In other words, although the Deepwater Horizon possessed

characteristics associated with transportation, those characteristics played no 

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role in the disaster, and the accident was not related to transportation. We 

agree with the district court that § 1131(a)(1)(F) is inapplicable and that the 

NTSB lacked jurisdiction to investigate the incident under that provision, 

meaning that the CSB was authorized to act.

IV.

For the reasons stated above, we conclude that the CSB had jurisdiction 

to investigate the incident at the Macondo well and to issue the administrative 

subpoenas. The district court’s judgment ordering enforcement of the 

subpoenas is therefore AFFIRMED.

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JONES, Circuit Judge, dissenting. 

I respectfully disagree with the majority opinion, which assists the 

United States Chemical Safety Board (“CSB”) in expanding its jurisdiction into 

novel territory disallowed by Congress. This is the first time, in twenty years 

after CSB was ordained, that the agency has sought to investigate in 

connection with an offshore oil spill.1 The majority’s interpretation of the 

Clean Air Act disregards the plain meaning of words and grammar and the 

most fundamental maritime concept, which is the definition of a vessel. To 

summarize my view: the Mobile Offshore Drilling Unit Deepwater Horizon 

was a vessel, not a “stationary source” pursuant to 42 U.S.C. § 7412(r)(2)(C), 

and the Macondo Well blowout caused a “marine oil spill,” 42 U.S.C. 

§ 7412(r)(6)(E), which excluded the blowout from CSB jurisdiction either in toto 

or because the NTSB was empowered to investigate. 

Because the majority opinion aptly describes the background of this 

controversy, only a bit need be repeated here. Transocean objects to 

administrative subpoenas served by CSB when the agency instituted an 

investigation following the Deepwater Horizon oil spill disaster. The standard 

for challenging an administrative subpoena is strict: courts may only interfere 

with the process in a limited number of circumstances, one of which arises 

when the agency plainly lacks jurisdiction. See Burlington N. R. Co. v. Office 

of Inspector Gen., R.R. Ret. Bd., 983 F.2d 631, 638 (5th Cir. 1993); see also 

United States v. Powell, 379 U.S. 48, 57–58, 85 S. Ct. 248, 255 (1964). CSB 

was created as a Clean Air Act counterpart to the National Traffic Safety Board 

(“NTSB”) and charged with investigating unanticipated releases of hazardous 

substances into the ambient air from “stationary sources.” 42 U.S.C. 

§ 7412(r)(2)(C) (defining the term “accidental release” found in 42 U.S.C. 

1 Inside OSHA, Vol. 17, No. 13, at 6 (June 29, 2010).

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§ 7412(r)(6)(C)(i)). The term “stationary sources,” includes “any buildings, 

structures, equipment, installations or substance emitting stationary 

activities. . . ." 42 U.S.C. § 7412(r)(2)(C). The Board may follow up an 

investigation by recommending regulatory measures to avert future releases 

into the air. NTSB, in contrast, investigates “transportation-related” aviation, 

highway, rail, marine or pipeline accidents and also makes regulatory 

recommendations to improve safety. 49 U.S.C. § 1131(a)(1)(F). Not only CSB 

and NTSB, but numerous other agencies either routinely or at special request 

investigate accidents with significant public impact. As a result, the statute 

that created CSB requires this agency to cooperate with or take a second seat 

to such agencies: 

The Board shall coordinate its activities with investigations 

and studies conducted by other agencies of the United States 

having a responsibility to protect public health and safety. The 

Board shall enter into a memorandum of understanding with the 

National Transportation Safety Board to assure coordination of 

functions and to limit duplication of activities which shall 

designate the National Transportation Safety Board as the lead 

agency for the investigation of releases which are transportation 

related. The Board shall not be authorized to investigate marine 

oil spills, which the National Transportation Safety Board is 

authorized to investigate. The Board shall enter into a 

memorandum of understanding with the Occupational Safety and 

Health Administration so as to limit duplication of activities. In no 

event shall the Board forego an investigation where an accidental 

release causes a fatality or serious injury among the general 

public, or had the potential to cause substantial property damage 

or a number of deaths or injuries among the general public.

42 U.S.C. § 7412(r)(6)(E).

Under this provision, if the Deepwater Horizon was not a stationary 

source, CSB lacked the authority to investigate. Likewise, if the disaster was 

a marine oil spill, or by even the majority’s construction a marine oil spill that

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NTSB was authorized to investigate, CSB lacks authority. I will discuss each 

of these limits on CSB’s authority in turn.

1. Can a vessel be a “stationary source”?

This question seems to answer itself. A “vessel,” as defined in federal 

law, is a device capable of providing transportation on water. 1 U.S.C. § 3; 

Stewart v. Dutra Construction Co., 543 U.S. 481, 495, 125 S. Ct. 1118, 1128 

(2005). “Stationary” means “fixed in a station, course or mode; unchanging, 

stable, static.” Webster's Third New International Dictionary 2229 (1986). Not 

only does “stationary” modify all of the following terms, but the following 

illustrations of “stationary sources” are inherently fixed and immobile 

(“buildings, structures, equipment, installations . . .”). A vessel capable of 

transportation is not comparable to these illustrated sources and cannot be a 

stationary source of emissions. To so conclude erases the line between 

stationary and mobile sources. 

 But the majority determines otherwise. First, the majority opinion 

acknowledges that the Deepwater Horizon is a vessel according to Coast Guard 

regulations, Supreme Court authority, longstanding case law in this circuit, 

and multiple decisions relating to this oil spill disaster. However, the majority 

contends, what is good law for maritime purposes does not govern the Clean 

Air Act’s statutory definition. Alternatively, the majority holds, the Deepwater 

Horizon was in fact “stationary” when the blowout and oil spill occurred, 

because its dynamic positioning devices kept the unit essentially in place 

without anchors securing it to the ocean floor while it engaged in drilling 

operations. Finally, the majority posits that the “Macondo drilling installation 

as a whole,” allegedly encompassing the drill string, riser, blowout preventer, 

wellhead and casing, all of which stretch over a mile down and into the Outer 

Continental Shelf seabed, maintained a stationary position. 

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The majority’s fundamental error lies in distorting “stationary” from its 

ordinary meaning, as required by the tools of statutory interpretation, Castro 

v. Collecto, Inc., 634 F.3d 779, 786 (5th Cir. 2011). The Deepwater Horizon 

was a “vessel” from a common sense standpoint. Technically, it was a 

“dynamically-positioned semi-submersible drilling vessel” that was afloat and 

under movement at the time of the blowout. See In re Oil Spill by the Oil Rig 

Deepwater Horizon in the Gulf of Mexico, on April 20, 2010, 808 F. Supp. 2d 

943, 950 (E.D. La. 2011), aff'd sub nom. In re Deepwater Horizon, 745 F.3d 157 

(5th Cir. 2014). It navigated, transported personnel and equipment, and 

continued navigating in order to hold its position in the sea against currents 

and waves. That it was able to employ advanced technology to accomplish its 

purpose, rather than sails or rudders, does not detract from its status as a 

vessel; hence, its status as a “mobile” offshore drilling unit. At all times, it had 

a navigational crew in addition to a drilling crew. The issue here is not so 

much whether the Clean Air Act definition must slavishly follow the course of 

maritime law, but also whether calling this “mobile” offshore drilling a “vessel” 

conflicts with the ordinary meaning of a “stationary source.” 

Virtually every opinion of this court relating to the Deepwater Horizon 

oil spill disaster has referred to the MODU as a “vessel,”2 and in so doing we 

have followed a path charted in this court for decades. See, e.g., Trico Marine 

Operators, Inc. v. Falcon Drilling Co., 116 F.3d 159, 161 (5th Cir. 1997); 

Dougherty v. Santa Fe Marine, Inc., 698 F.2d 232, 234 (5th Cir. 1983); Offshore 

Co. v. Robison, 266 F.2d 769, 779 (5th Cir. 1959). Our decisions reflect how 

2 See, e.g., In re Deepwater Horizon, 753 F.3d 570, 571 (5th Cir. 2014); In re Deepwater 

Horizon, 745 F.3d 157, 164 (5th Cir. 2014); In re Deepwater Horizon, 739 F.3d 790, 796 (5th 

Cir. 2014) (labeling the MODU as a vessel).

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maritime activities have evolved in the last fifty years to include new and evermore-sophisticated watercraft. The Supreme Court has also defined “vessels” 

expansively as “any watercraft practically capable of maritime transportation.” 

Stewart v. Dutra Constr. Co., 543 U.S. 481, 497, 125 S. Ct. 1118, 1128 (2005). 

Also compelling is the Coast Guard’s responsibility for regulating mobile 

offshore drilling units, which recently led it to conclude that if anything, their 

status as vessels should be fortified. Memorandum from S.D. Poulin, U.S. 

Coast Guard, to CG-5, Potential Legal Issues Associated With Vessels 

Employing Dynamic Positioning Systems 10 (Feb. 11, 2011). Why, in the face 

of ordinary meaning and this body of consistent authority, should a court be 

able to hold that the Deepwater Horizon, although a “vessel,” was a “stationary 

source”? This is like holding a pig is a pony. The language of the statute is 

broad but it isn’t limitless. Either “stationary” means something related to 

immobility, or judges are making up a new meaning. 

The majority’s other reasons for holding that the Deepwater Horizon was 

a “stationary source” also defy common sense. The majority’s description of 

the sophisticated dynamic positioning system used by Mobile Offshore Drilling 

Units like the Deepwater Horizon is flawed and, worse, leads to the possibility 

that CSB jurisdiction will turn on fact-specific determinations of “stationary” 

versus “mobile” sources. Factually, it is true that the thrusters operated by 

the MODU’s navigational crew kept the unit positioned substantially over the 

wellhead, but the unit continues at all times to move with the wave motions. 

Essentially, the thrusters permit the unit to tread water. Anyone treading 

water, however, is constantly in motion, and so was the Deepwater Horizon. 

Likewise, a helicopter may hover in place over the ground, but it is always in 

motion, and I suppose even CSB would not contend it is a “stationary source.” 

Even more unfortunate is the resort to fact-specific reasoning to 

determine that this vessel is a “stationary source.” Since the statute draws a 

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dichotomy between the CSB’s responsibility for “stationary source” accidental 

air releases and NTSB’s jurisdiction over “transportation-related” disasters, 

the CSB’s aggressive attempt to blur the dichotomy is at odds with the statute 

itself. (As will be seen, CSB is horning into the primary jurisdiction of NTSB 

by urging this court to narrow NTSB’s scope as well.) Of course, the statute 

contemplates splitting duties between NTSB and CSB in appropriate cases, 

and in such cases requiring CSB to yield to NTSB, but one can easily envision 

overlaps without CSB’s having to mutilate the definition of “stationary.” For 

instance, if a chemical tank exploded at a rail yard and emitted hazardous 

fumes, there could be a question whether the cause was transportation-related 

or due to a stationary source nearby. Similarly, toxic substances or fuel used 

in connection with aircraft and aircraft maintenance might ignite at an 

aviation center, emitting hazardous air pollutants. The cause of either 

accident could be “stationary” or “transportation-related.” In the Deepwater 

Horizon disaster, however, CSB contends that the vessel itself was the 

“stationary source” because it was dynamically positioned. Henceforth, the 

same argument could result in fully overlapping CSB/NTSB authority 

whenever a vehicle, aircraft, or vessel happens to be temporarily moored at the 

time of an unanticipated toxic air emission.

The majority’s final rationale for calling this mobile offshore drilling unit 

a “stationary source” is to embed it in an “installation as a whole” 

encompassing the Macondo well and the well’s casing3 and wellhead, 4 which 

3 Casing, SCHLUMBERGER OILFIELD GLOSSARY, (last visited Sept. 16, 2014), 

http://www.glossary.oilfield.slb.com/en/Terms/c/casing.aspx (“Large-diameter pipe lowered 

into an openhole and cemented in place.”).

4 Wellhead, SCHLUMBERGER OILFIELD GLOSSARY, (last visited Sept. 16, 2014), 

http://www.glossary.oilfield.slb.com/en/Terms/w/wellhead.aspx (“The system of spools, valves 

and assorted adapters that provide pressure control of a production well.”).

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are located underneath or at the level of the seabed. This bottom-up logic is 

erroneous for two reasons. 

First, common sense tells us that the five thousand feet of drill string, 

plus riser and blowout preventer leading from the MODU to the well hardly 

created a stationary island 50 miles off the United States coast in the Gulf of 

Mexico. The MODU Deepwater Horizon and its appurtenances are connected 

to the seabed.5 But it is quite inconsistent to say that the “installation” is 

stationary when the only reason for its being stationary is that the vessel uses 

dynamic positioning thrusters and is constantly in motion to maintain stability 

over the wellhead. Broadening the term “installation” to denominate the 

Macondo well and the Deepwater Horizon a “stationary source” is nothing 

more than rhetorical legerdemain designed to obfuscate the limits on CSB’s 

jurisdiction.

Second, both statutory law and well settled case law have distinguished 

between fixed and mobile drilling platforms and offshore devices for decades. 

The Outer Continental Shelf Lands Act distinguishes between “artificial 

islands” and vessels in order to demarcate between the application of federal 

or state law and admiralty law. See 43 U.S.C. § 1333(1) (distinguishing 

between artificial islands subject to the choice of law provisions of 

43 § 1333(2)(A) and vessels not subject to such provisions); see also Herb's 

Welding, Inc. v. Gray, 470 U.S. 414, 421–23, 105 S. Ct. 1421, 1426–27 (1985)

(outlining the division between artificial islands subject to “borrowed state 

5 The majority’s bottom-up logic is hard to square with a recent opinion of this Court 

that referred to the blowout preventer and riser as “appurtenances” of the vessel Deepwater 

Horizon, and the vessel and its appurtenances as separate from the well. In re Deepwater 

Horizon, 753 F.3d 570, 571 (5th Cir. 2014); Jerome B. Grubart, Inc. v. Great Lakes Dredge & 

Dock Co., 513 U.S. 527, 535, 115 S. Ct. 1043, 1049 (1995) ([M]aritime law ... ordinarily treats 

an “appurtenance” attached to a vessel in navigable waters as part of the vessel itself.”).

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law” and other areas subject to maritime law). Artificial islands are drilling or 

production platforms attached to the seabed in some way and thus fully 

immobile, while other special purpose structures “such as jack-up rigs, 

submersible drilling barges, derrick barges, spud barges, and others are 

vessels as a matter of law.” Manuel v. P.A.W. Drilling & Well Service, Inc., 

135 F.3d 344, 347 (5th Cir. 1998). It is bedrock that “[w]e assume that 

Congress is aware of existing law when it passes legislation.” Miles v. Apex 

Marine Corp., 498 U.S. 19, 32 (1990); see also Goodyear Atomic Corp. v. Miller, 

486 U.S. 174, 184–85, 108 S. Ct. 1704, 1712 (1988) (“We generally presume 

that Congress is knowledgeable about existing law pertinent to the legislation 

it enacts."). Setting aside the “marine oil spill exclusion” discussed next, the 

CSB’s jurisdiction over artificial islands as “stationary” sources fits 

comfortably within the OCSLA dichotomy and background law. Just as 

clearly, characterizing the MODU Deepwater Horizon with or without the 

Macondo well as “stationary” does not. The majority’s deviation from 

background law violates the ordinary interpretive presumption as well as the 

facts. 

2. Can the "marine oil spill exclusion" be excluded?

It is unnecessary to wade into the parties’ “comma, which” dispute to 

reach a sensible interpretation of 42 U.S.C. § 7412(r)(6)(C)(i), which excludes 

marine oil spills from CSB’s investigative authority. This provision as a whole 

expresses Congress’s recognition that other agencies have regulatory 

jurisdiction over hazardous releases into the ambient air. Consequently, CSB 

has to cooperate and coordinate with such agencies in furtherance of public 

health and safety. Foreseeing significant potential overlaps, Congress paid 

particular attention to the interrelation of CSB with two agencies: the OSHA 

and NTSB. NTSB, relevant here, is deemed the lead agency for releases 

“which” are “transportation related.” We know from the Supreme Court that 

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“related-to” language is enabling in the broadest sense. Ingersoll-Rand Co. v. 

McClendon, 498 U.S. 133, 138–39, 111 S. Ct. 478, 482–83 (1990) (discussing 

the breadth of the “related-to” pre-emption language in § 514(a) of ERISA). 

The CSB, moreover, “shall not be authorized to investigate marine oil spills, 

which the National Transportation Safety Board is authorized to investigate.” 

Nevertheless, “[i]n no event shall the [CSB] forego an investigation where an 

accidental release causes a fatality or serious injury among the general public

or had the potential to cause substantial property damage or a number of 

deaths or injuries among the general public.” I part company with the majority 

on the applicability of the “marine oil spill exclusion” and their interpretation 

of the “danger to the public” catchall language. 

Taking the “marine oil spill exclusion” first, even if this language is read 

holistically and narrowly to exclude CSB from only those marine oil spills 

“that” the NTSB may investigate, this marine oil spill was “related to” 

transportation through the movement of hydrocarbons from the well through 

the drill string to the Deepwater Horizon6 and by virtue of the vessel’s constant 

movement. On the face of the provision, where NTSB was authorized to 

investigate, CSB must recede. Curiously, however, to expand CSB jurisdiction, 

at the expense of the NTSB, the majority accepted two of CSB’s propositions: 

this oil spill disaster, the largest in American history, was not within the 

“marine oil spill exclusion,” and even if it was, NTSB lacked jurisdiction. These 

arguments are wrong. The first one would eviscerate the “marine oil spill 

exclusion” completely. The second erroneously limits NTSB’s authority.

Holding that the “marine oil spill exclusion” does not apply if hazardous 

substances were incidentally released into the air during a “marine oil spill” 

6 Recall that NTSB is also charged to investigate pipeline disasters.

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turns the exclusion on its head and renders it a nullity.7 Virtually any offshore 

crude oil spill involves the emission of fumes, because petroleum produced from 

wells is “oil,” more technically, "[a] complex mixture of naturally hydrocarbon 

compounds found in rock. . . . [T]he term is generally used to refer to liquid 

crude oil. Impurities, such as sulfur, oxygen and nitrogen are common in 

petroleum.” Petroleum, SCHLUMBERGER OILFIELD GLOSSARY, (last visited 

Sept. 16, 2014), www.glossary.oilfield.slb.com/en/Terms/p/petroleum.aspx. 

The lighter hydrocarbons and impurities in crude oil readily evaporate into the 

air; as we all know, there is no smoking at gas pumps because of the volatility 

of hydrocarbons in “oil.” CSB’s attempt to separate these mixed hydrocarbons 

temporally from the oil spill disaster, by purporting to focus its investigation 

on the emission of fumes that ignited and exploded at the platform, is 

unrealistic. How unrealistic is confirmed by the scope of the agency’s subpoena 

at issue here: CSB called for all of the documents that Transocean turned over 

to all of the other investigating agencies concerning the blowout, explosion and 

oil spill. Why? Because the liquid and gaseous hydrocarbons all spewed from 

the well due to the same errors during the drilling process. The investigation 

cannot be limited to ambient air releases apart from the events that triggered 

the marine oil spill. This position is factually unsupportable.

Equally untenable is the holding that NTSB lacked authority to 

investigate this disaster. NTSB has jurisdiction over “any other accident 

related to the transportation of individuals or property when the [NTSB] 

decides--

(i) the accident is catastrophic;

(ii) the accident involves problems of a recurring 

7 It is an established principle of statutory interpretation that “[w]here possible, every 

word in a statute should be given meaning.” G.M. Trading Corp. v. C.I.R., 121 F.3d 977, 981 

(5th Cir. 1997).

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 character; or

(iii) the investigation of the accident would carry

 out this chapter.

49 U.S.C. § 1131(a)(1)(F). The majority fall back on their faulty conclusion that 

the oil spill disaster was not “transportation related.”8 Remarkably, the 

majority must conclude that “[m]erely because a disaster involves a vessel does 

not mean that the disaster was necessarily related to transportation.” I have 

already explained why the MODU’s status as a vessel is dispositive of the 

“stationary source” argument; the factual and legal points made there apply 

even more clearly to this argument. The logical implication of the majority’s 

interpretation forbids NTSB to operate in its area of expertise when certain 

catastrophic disasters involve a temporarily immobile vehicle, airplane, train, 

vessel or pipeline activity. The settled legal interpretation of "related" forbids 

this artificial constraint.

Finally, the majority erroneously relies on CSB’s catchall investigative 

power over fatalities, serious injuries or property damages to “the general 

public.” 42 U.S.C. § 7412(r)(6)(E). The Deepwater Horizon’s crew were 

specialized oilfield or marine employees covered by OSHA, not “the general 

public.” To be sure, this catchall is an empowering provision, just as 

Section 1131(a)(1)(F) is empowering to the NTSB. Unlike the NTSB provision, 

which empowers transportation “related” investigations, CSB’s provision 

covers actual or potential injuries, fatalities or property damage to “the general 

public.” On the facts of this case, the provision is clearly inapplicable. CSB 

posits its jurisdiction only over the explosion on the MODU Deepwater Horizon 

8 The present case involves an accident on the Outer Continental Shelf and is therefore 

unlike NTSB v. Carnival Cruise Lines, Inc., 723 F. Supp. 1488, 1493 (S.D. Fla. 1989), which 

dealt with an “extraterritorial investigation” outside of U.S. territory. Since 43 U.S.C. 

§ 1331(a) makes clear that the Outer Continental Shelf is under U.S. law, any investigation 

would not be extraterritorial. 

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that was occasioned by the release of volatile hydrocarbons from the well. The 

Macondo well was located 50 miles offshore of Louisiana. No one has ever 

claimed that injury occurred to “the general public” onshore from releases into 

the ambient air. The term “public” is defined to mean “of, relating to, or

affecting the people as an organized community.” Webster’s Third New 

International Dictionary 1836 (1986); see also Black’s Law Dictionary 1264 

(8th ed. 1999) (defining public as “[r]elating or belonging to an entire 

community”). The workers who tragically lost their lives in the vessel’s 

explosion are not, under this definition, “the general public.” Congress could 

have easily described CSB’s catchall jurisdiction by referring to “individuals” 

or “any person,” but it chose a different term. 

Conclusion

This case strictly and properly concerns an agency’s statutory authority 

to issue subpoenas and conduct an investigation. The much broader 

ramifications of the decision should not, however, be overlooked. First, when 

Congress has delineated agency authority against clear background principles 

and with easily defined terms, the agency itself should not play havoc with the 

statute to expand its authority; an agency has a duty to follow its mandate but 

go no further. For the sake of maintaining limited government under the rule 

of law, courts must be vigilant to sanction improper administrative overreach. 

See, e.g., Util. Air Regulatory Grp. v. E.P.A., 134 S. Ct. 2427, 2449 (2014)

(holding that the EPA exceeded its statutory authority). Second, contrary to 

some fears expressed about the consequences of holding CSB unable to 

investigate the Deepwater Horizon disaster, there were at least seventeen 

investigations, including major reports by a Presidential Commission and the 

Coast Guard. See Exec. Order No. 13,543, 75 Fed. Reg. 29,397 (May 21, 2010)

(establishing the National Commission on the BP Deepwater Horizon Oil Spill 

and Offshore Drilling). The Coast Guard, in fact, was required to “make an 

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investigation and public report on each major fire and each major oil spillage 

occurring as a result of” exploration, development and production of minerals 

from the OCS. 43 U.S.C. § 1348(d)(1). There is no dearth of proper 

investigation to protect public safety. Third, as a result of being deemed by 

this opinion “stationary sources,” nearly all non-standard offshore vessels 

involved in oil and gas production on the OCS will become subject to Clean Air 

Act regulation and reports in addition to “all of the regulatory requirements of 

‘traditional’ vessels” imposed by the Coast Guard. See 42 U.S.C. 

§ 7412(r)(7)(B)(iii); Memorandum from S.D. Poulin, U.S. Coast Guard, to CG5, Potential Legal Issues Associated With Vessels Employing Dynamic 

Positioning Systems 10 (Feb. 11, 2011). 

For all these reasons, I respectfully dissent. 

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