                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

CHRISTOPHER MACDONALD,                
               Plaintiff-Appellant,         No. 08-15239
                v.
                                             D.C. No.
                                          CV-02-00084-LEK
KAHIKOLU, LTD., doing business as
Frogman Charters,                            OPINION
              Defendant-Appellee.
                                      
       Appeal from the United States District Court
                for the District of Hawaii
     Leslie E. Kobayashi, Magistrate Judge, Presiding

                  Argued and Submitted
         June 12, 2009—San Francisco, California

                 Filed September 10, 2009

       Before: Procter Hug, Jr., Betty B. Fletcher and
          Michael Daly Hawkins, Circuit Judges.

               Opinion by Judge B. Fletcher




                           13143
                MACDONALD v. KAHIKOLU, LTD.            13145




                        COUNSEL

John R. Hillsman, McGuinn, Hillsman & Palefsky, San Fran-
cisco, California; Howard G. McPherson, Cronin, Fried,
Sekiya, Kekina & Fairbanks, Honolulu, Hawaii, for the
plaintiff-appellant.

Richard C. Wootton and Mitchell S. Griffin, Cox, Wootton,
Griffin, Hansen & Poulos, LLP, San Francisco, California, for
the defendant-appellee.
13146           MACDONALD v. KAHIKOLU, LTD.
                          OPINION

B. FLETCHER, Circuit Judge:

   For a second time, plaintiff Christopher MacDonald
appeals the district court’s judgment after a bench trial in his
Jones Act suit against defendant Kahikolu, Ltd. MacDonald
worked as a crew member aboard one of Kahikolu’s ships and
was injured while performing a “free dive,” an underwater
dive done on a single breath without scuba equipment or other
underwater breathing apparatus. In a prior opinion, a separate
panel of this court vacated the district court’s judgment, and
remanded for the district court to consider whether Kahikolu’s
failure to comply with Coast Guard regulations played any
part in causing MacDonald’s injuries. See MacDonald v.
Kahikolu Ltd., 442 F.3d 1199, 1200 (9th Cir. 2006). On
remand, the district court held that Kahikolu’s failure to com-
ply with the regulations did not cause MacDonald’s injuries
and again entered judgment for the company. MacDonald
appeals, arguing that the district court should have applied the
rule from The Pennsylvania, 86 U.S. (1 Wall.) 125, 136
(1873), which puts on the ship owner the burden of proving
that its violation of a statute or regulation did not cause the
injury.

   We have jurisdiction under 28 U.S.C. § 1291. Because we
conclude that the Pennsylvania Rule does not apply here, we
affirm.

                               I.

  The factual background is set forth in MacDonald, and we
reprise it here only insofar as is necessary.

  Kahikolu conducts whale watching, scuba, and snorkeling
tours off the coast of Maui, Hawaii. MacDonald, 442 F.3d at
1200. MacDonald worked as a deck hand and lifeguard for
Kahikolu and, as part of his job, periodically made free dives.
                    MACDONALD v. KAHIKOLU, LTD.                      13147
Id. On one outing, MacDonald was working aboard
Kahikolu’s Frogman II and undertook a free dive to retrieve
a mooring line from the sea floor, a depth of about 46 feet. Id.
However, as he descended to the sea floor, he injured his left
ear trying to equalize the pressure in his ears.1 Id. As a result,
MacDonald had to be treated for permanent hearing loss, diz-
ziness, and tinnitus. Id.

   MacDonald sued Kahikolu, alleging a violation of the
Jones Act, 46 U.S.C. § 30104, for failure to provide a safe
work environment, among other claims.2 Id. After a bench
trial, the district court found that MacDonald was an experi-
enced free diver who regularly had made many dives to
depths of 30, 40, and 50 feet without ear pain or injury. Id. at
1201. The court also found that Kahikolu employees had
made thousands of free dives without injury and that the
activity was not inherently dangerous. Id. Although the court
found that Kahikolu had inadequately trained MacDonald
regarding free dives, the court ultimately found Kahikolu not
negligent because it did not have notice of any unsafe condi-
tion. Id.

   Before the district court and in his prior appeal, MacDonald
argued that Kahikolu was negligent per se, because it had not
complied with Coast Guard regulation 46 C.F.R.
§ 197.420(a)(1), which required the company to provide an
  1
     Being underwater exerts pressure on a diver in excess of that at sea
level, creating a pressure differential between the ambient environment
and internal cavities such as the sinuses and middle ear. The pressure can
be equalized using what is called the “Valsalva maneuver,” which
involves holding the nose and gently blowing. See MacDonald, 442 F.3d
at 1200 n.2. Injury occurs if the diver blows too forcefully or too long. Id.
   2
     The Jones Act provides that “[a] seaman injured in the course of
employment or, if the seaman dies from the injury, the personal represen-
tative of the seaman may elect to bring a civil action at law, with the right
of trial by jury, against the employer,” under the same laws applying to
such suits by railway employees, i.e., the Federal Employers’ Liability
Act, 45 U.S.C. § 51. 46 U.S.C. § 30104.
13148                 MACDONALD v. KAHIKOLU, LTD.
operations manual to the person in charge of the dive.3 Id. at
1200. The district court rejected this theory, because it held
that the regulations applied only to commercial scuba divers,
not to free divers. Id. at 1201.

  On appeal, we reversed the district court out of concern that
  3
   46 C.F.R. § 197.420 states:
      (a) The diving supervisor shall—
         (1) Provide an operations manual to the person-in-charge prior
      to commencement of any diving operation; and
         (2) Make an operations manual available at the dive location
      to all members of the dive team.
  ***
      (c) The operations manual must provide for the safety and health
      of the divers.
      (d) The operations manual must contain the following:
        (1) Safety procedures and checklists for each diving mode
      used.
        (2) Assignments and responsibilities of each dive team mem-
      ber for each diving mode used.
        (3) Equipment procedures and checklists for each diving mode
      used.
        (4) Emergency procedures for—
          (i) Fire;
          (ii) Equipment failure;
          (iii) Adverse environmental conditions including, but not
          limited to, weather and sea state;
          (iv) Medical illness; and
          (v) Treatment of injury.
        (5) Procedures dealing with the use of—
          (i) Hand-held power tools;
          (ii) Welding and burning equipment; and
          (iii) Explosives.
                 MACDONALD v. KAHIKOLU, LTD.               13149
the court erred in failing to consider the applicability of Ker-
nan v. American Dredging Co., 355 U.S. 426 (1958). In Ker-
nan, the Supreme Court held that under the Federal
Employers’ Liability Act and the Jones Act, an employer is
liable for the injury or death of an employee if it is caused “in
whole or in part[ ] by the employer’s fault,” including by
breach of a common law or statutory duty. Id. at 432. Kernan
thus dispenses with the traditional negligence per se require-
ment that the statute must be designed to prevent the kind of
injury actually at issue. See MacDonald, 442 F.3d at 1203.
Pursuant to Kernan, MacDonald would be entitled to recover
damages if Kahikolu’s violation played any part in causing
his injury, no matter how slight. Id.

  We remanded with the following instructions:

    The record shows that the commercial diving regula-
    tions expressly applied only to persons using under-
    water breathing apparatus and not to free divers. It
    is not clear, however, whether the district court
    applied the appropriate causation standard in deter-
    mining that Kahikolu was not liable for Mr. Mac-
    Donald’s injuries. Accordingly, we vacate the
    judgment and remand with instructions that the dis-
    trict court determine whether the failure of Kahikolu
    to comply with Coast Guard regulations played any
    part, “ ‘even the slightest,’ ” in producing Mr. Mac-
    Donald’s injuries and enter a new judgment in accor-
    dance with that finding.

Id. (citation omitted).

   On remand, the district court again found in favor of
Kahikolu. While the regulations required Kahikolu to have a
dive operations manual aboard the Frogman II, the district
court found “little, if any, evidence to support Plaintiff ’s con-
tention that the absence of a dive manual aboard the vessel
contributed, even in the slightest, to Plaintiff ’s injuries.”
13150            MACDONALD v. KAHIKOLU, LTD.
According to the district court, the applicable regulations are
“simply void of any discussion relating to free diving,” so
having an operations manual would not have affected what
happened to MacDonald on his free dive. Thus, the district
court concluded that Kahikolu’s failure to comply with the
applicable Coast Guard regulations did not play any part in
producing MacDonald’s injuries.

   In so deciding, the district court declined to apply the Penn-
sylvania Rule, and alternatively held that even if the Pennsyl-
vania Rule applied, Kahikolu had met its burden under the
Rule. MacDonald now challenges those decisions.

                               II.

   We review the district court’s conclusions of law, including
whether the Pennsylvania Rule applies, de novo. Ambassador
Hotel Co. v. Wei-Chuan Investment, 189 F.3d 1017, 1024 (9th
Cir. 1999). Findings of fact following a bench trial are
reviewed for clear error. Id. If the Pennsylvania Rule applies,
application of the Rule to the facts is also reviewed for clear
error. See Churchill v. F/V Fjord, 892 F.2d 763, 770 (9th Cir.
1988); Trinidad Corp. v. S.S. Keiyoh Maru, 845 F.2d 818, 827
(9th Cir. 1988).

                              III.

   The Pennsylvania Rule is a longstanding rule of admiralty
law, and we have often applied it in this circuit. See, e.g.,
Exxon Co. v. Sofec, Inc., 54 F.3d 570, 577 (9th Cir. 1995);
Trinidad Corp., 845 F.2d at 825; see also Mathes v. Clipper
Fleet, 774 F.2d 980, 982 (9th Cir. 1985) (listing cases). Under
the Rule, if a vessel involved in an accident violated a statute
or regulation intended to prevent such an incident, it is pre-
sumed that the ship owner was at fault, and the burden of
proving causation shifts to the ship owner. See The Pennsyl-
vania, 86 U.S. (19 Wall.) at 136. As the Supreme Court
explained,
                    MACDONALD v. KAHIKOLU, LTD.                       13151
     The liability for damages is upon the ship or ships
     whose fault caused the injury. But when, as in this
     case, a ship at the time of a collision is in actual vio-
     lation of a statutory rule intended to prevent colli-
     sions, it is no more than a reasonable presumption
     that the fault, if not the sole cause, was at least a con-
     tributory cause of the disaster. In such a case, the
     burden rests upon the ship of showing not merely
     that her fault might not have been one of the causes,
     or that it probably was not, but that it could not have
     been.

Id. The Court justified imposing such a heavy burden by stat-
ing that the rule “is necessary to enforce obedience to the
mandate of the statute.”4 See id. at 136.

   [1] The burden imposed by the Pennsylvania Rule has been
described as “ ‘difficult, if not impossible,’ ” to discharge.
Trinidad Corp., 845 F.2d at 825 (quoting Ishizaki Kisen Co.
v. United States, 510 F.2d 875, 879 (9th Cir. 1975)). Never-
theless, the presumption is rebutted where the defendant
shows by clear and convincing evidence that the violation
could not reasonably be held to have been a proximate cause
of the injury. Id. at 824 (quoting States S.S. Co. v. Permanente
S.S. Corp., 231 F.2d 82, 87 (9th Cir. 1956)).

   It is undisputed that Kahikolu violated 46 C.F.R. § 197.420
by not having an operations manual aboard the ship at the
time of MacDonald’s accident. MacDonald also argues that
Kahikolu failed to designate a “person-in-charge” of the ves-
sel and a “diving supervisor,” as required by 46 C.F.R.
§§ 197.208(a) and 197.210(a).5
   4
     The Rule now applies to violations of either statutes or regulations. See
Mathes, 774 F.2d at 982 n.1.
   5
     Under the regulations, the diving supervisor must be “fully cognizant
of the provisions of the operations manual required by § 197.420” and is
“in charge of the planning and execution of the diving operation including
the responsibility for the safety and health of the dive team.” 46 C.F.R.
§ 197.404(a)(2), (b).
13152              MACDONALD v. KAHIKOLU, LTD.
   Despite these regulatory violations, it is not clear that the
Pennsylvania Rule applies to cases that do not involve a colli-
sion or other “navigational” accident, or to claims made under
the Jones Act. In Mathes, we decided that the Rule did not
apply to a personal injury claim brought by a plaintiff whose
foot was pinned between two ships. 774 F.2d at 982-83. The
crew member on one of the ships did not have a local
endorsement aboard the ship, as required by Coast Guard reg-
ulations. Id. at 983. We declined to apply the Rule, because
there was “no conceivable causal connection between the vio-
lation and the injury,” and under the Rule, “if it clearly
appears the fault could have had nothing to do with the disas-
ter, it may be dismissed from consideration.” Id. at 983 (cita-
tion omitted). We did not, however, explicitly address
whether the Pennsylvania Rule could apply to cases that do
not involve a collision or navigational accident, nor do any of
our prior cases do so.6

   Some other courts have applied the Rule broadly to non-
collision and non-navigation cases. For example, the Third
Circuit has stated that “[a]lthough the Rule originally applied
only to collisions between ships, it has been reformulated to
apply to any statutory violator who is a party to a maritime
accident.” In re Nautilus Motor Tanker, 85 F.3d 105, 113 (3d
Cir. 1996) (citing Pennzoil Producing Co. v. Offshore
Express, Inc., 943 F.2d 1465, 1471 (5th Cir. 1991)); see also
United States v. Nassau Marine Corp., 778 F.2d 1111, 1116
(5th Cir. 1985) (“The Rule does not apply only to colli-
sions.”); Reyes v. Vantage S.S. Co., 609 F.2d 140, 145-46 (5th
Cir. 1980) (applying Rule to Jones Act man-overboard case);
  6
    The Alaska Supreme Court in Marine Solution Services, Inc. v. Horton,
70 P.3d 393, 406-07 (Alaska 2003), interpreted Mathes as assuming that
the Rule applies to Jones Act personal injury claims. However, the plain-
tiff in Mathes sought to apply the Rule to a third party, not to his
employer, so it was not, strictly speaking, a Jones Act claim. See Mathes,
774 F.2d at 981-83. In any event, Mathes did not discuss at all whether
the Rule did or should apply to personal injury claims and ultimately
found that the Rule did not apply.
                    MACDONALD v. KAHIKOLU, LTD.                      13153
In re Seaboard Shipping Corp., 449 F.2d 132, 136 (2d Cir.
1971) (applying Rule to man-overboard case and stating that
defendant was wrong “in its contention that admiralty applies
this rule only in collision cases”). However, beyond man-
overboard cases, no court has applied the Rule to a Jones Act
claim, except for the Alaska Supreme Court in Horton. 70
P.3d at 407. Indeed, although the Second Circuit applied the
Pennsylvania Rule in Seaboard Shipping, a Jones Act case, it
also stated in another Jones Act case—decided the same year
as Seaboard Shipping—that it would not extend the Rule
beyond “the chosen area of ship collisions.” Wilkins v. Am.
Export Isbrandtsen Lines, Inc., 446 F.2d 480, 486 (2d Cir.
1971). It recently has reiterated its skepticism about whether
the Rule should apply to Jones Act claims at all. See Wills v.
Amerada Hess Corp., 379 F.3d 32, 43-45 (2d Cir. 2004)
(“Even if we were persuaded that The Pennsylvania Rule
should be applied in some Jones Act cases, we would still
decline to apply the rule in cases where, as here, it cannot be
said with confidence that the plaintiff ’s injury resulted from
defendant’s actions.”).

   [2] In this case, we need not decide how far the Pennsylva-
nia Rule reaches beyond its traditional domain of ship colli-
sions and navigational accidents, because even if the Rule
applies to Jones Act claims, it would not apply here. All
courts have consistently required that there be a threshold
causal connection between the violation and the injury before
the Rule will apply. See, e.g., Mathes, 774 F.2d at 983; Wills,
379 F.3d at 44; Seaboard Tug & Barge v. Rederi AB/Disa,
213 F.3d 772, 775 (1st Cir. 1954); Horton, 70 P.3d at 407. In
part, this has meant that the injury must be of the kind
intended to be prevented by the statute or regulation that the
defendant violated.7 See Wills, 379 F.3d at 43 (holding that
  7
   It is this requirement that illustrates one of the differences between the
Pennsylvania Rule and negligence per se after Kernan. Kernan dispenses
with the traditional negligence per se requirement that the statute must be
designed to prevent the kind of injury actually at issue. See MacDonald,
13154               MACDONALD v. KAHIKOLU, LTD.
application of the Rule is “limited to the violation of a statute
intended to prevent the catastrophe which actually tran-
spired”); Nautilus Motor Tanker Co., 85 F.3d at 114 (requir-
ing three elements to be met for the Rule to apply: “(1) proof
by a preponderance of the evidence of violation of a statute
or regulation that imposes a mandatory duty; (2) the statute or
regulation must involve marine safety or navigation; and (3)
the injury suffered must be of a nature that the statute or regu-
lation was intended to prevent”); Folkstone Mar., Ltd. v. CSX
Corp., 64 F.3d 1037, 1047 (7th Cir. 1995) (adopting same);
Nassau Marine Corp., 778 F.2d at 1116 (stating that the Rule
“generally has been limited, at least in cases not involving
collisions and allisions, to violations of statutes intended to
prevent the injury that actually occurred”); see also 2 Thomas
J. Schoenbaum, Admiralty and Maritime Law § 14-3, at 102
(4th ed. 2004). Because the regulations here were not
intended to protect against the injuries MacDonald suffered,
the Pennsylvania Rule does not apply to Kahikolu, regardless
of the extent of its reach.

   [3] First, as the prior panel noted, “the commercial diving
regulations expressly appl[y] only to persons using underwa-
ter breathing apparatus and not to free divers.” MacDonald,
442 F.3d at 1203; see 46 C.F.R. §§ 197.202(a) (stating that
regulations apply to commercial diving operations), § 197.204

442 F.3d at 1203. Thus, given the relaxed causation standard under the
Jones Act, liability follows if there was a violation of any statute or regula-
tion that played any part in producing the injury, even the slightest. The
Pennsylvania Rule, by contrast, still retains the requirement that the statute
be intended to protect against the type of injury that in fact occurred.
Additionally, the Pennsylvania Rule does not establish negligence; it con-
cerns itself only with the burden of showing causation. See Mathes, 774
F.2d at 983 (“The only relevant difference between the two theories is that
the per se rule requires the plaintiff to prove causation whereas the Penn-
sylvania Rule shifts the burden of proof on causation to the defendant.”).
Assuming the Rule applied here, Kahikolu would have the burden of
showing that its violation of the regulation did not play any part in causing
MacDonald’s injury.
                  MACDONALD v. KAHIKOLU, LTD.                  13155
(defining “commercial diving operation” as activities in sup-
port of a “commercial diver” and “diver” as someone “using
underwater breathing apparatus”). So although the regulations
concern an activity similar to free diving, they do not address
free diving itself and are not intended to prevent injuries
incurred while free diving.8

   [4] Second, even insofar as a diving manual might possibly
have some bearing on Kahikolu’s free diving operations, it is
not mandatory that the manual contain restrictions or protocol
regarding free diving. This indicates both that the regulations
were not intended to protect against MacDonald’s injuries and
that there is no causal relationship between the lack of a div-
ing manual and MacDonald’s injuries. The regulations require
certain topics to be covered, such as safety procedures and
pre-dive checklists, but these do not require the manual to
address diving without any equipment or equalizing pressure
in one’s ears. See 46 C.F.R. § 197.420(c)-(d). MacDonald
contends that if Kahikolu had adopted a manual, it would
have imposed a depth restriction on free diving. But the regu-
lations do not explicitly require this, and nothing in the sub-
stance of the regulations suggests that Kahikolu had a duty to
impose such restrictions or any other diving procedure that
would have prevented MacDonald’s injury. See id.
§§ 197.404, 197.410, 197.420. By contrast, for example, 46
C.F.R. § 197.430 imposes mandatory restrictions on scuba
diving below 130 feet. See id. § 197.430(a). Since the Penn-
sylvania Rule is intended to enforce strict adherence to safety
regulations and statutes, the Rule applies only when a statute
or regulation actually imposes a mandatory duty. The regula-
tions here do not do so; therefore, the Rule does not apply.

  [5] We note finally that even if the Rule does apply, the
  8
   While the regulations were probably designed in part to prevent
barotrauma, their concern was with such injuries as suffered by scuba
divers or others using underwater breathing apparatuses, not with free
divers.
13156            MACDONALD v. KAHIKOLU, LTD.
district court’s assessment that Kahikolu had met its burden
was not clearly erroneous. Kahikolu established that its
employees had done numerous free dives before to a compa-
rable depth without injury, and Kahikolu’s expert testified
that free diving is not per se unsafe. The district court did not
clearly err in finding this to be clear and convincing evidence
that the failure to have a manual could not reasonably have
contributed to the injury. If Kahikolu had followed its own
experience and its expert’s opinion, it would not have put a
depth restriction on free dives. See Pacific Tow Boat Co. v.
States Marine Corp., 276 F.2d 745, 749 (9th Cir. 1960) (stat-
ing that the Rule “do[es] not require the vessel guilty of a stat-
utory fault to prove that its fault could not by any stretch of
the imagination have had any causal relation to the collision
no matter how speculative, improbable, or remote”). Mac-
Donald’s expert testified to the contrary, but even if the Penn-
sylvania Rule had shifted the burden of proof to Kahikolu,
this shift would not have required the district court to find for
MacDonald simply because the experts had contradictory
opinions; the Rule requires only that Kahikolu present clear
and convincing evidence sufficient to carry its burden of per-
suasion. There is no indication that the district court clearly
erred in crediting Kahikolu’s expert over MacDonald’s, espe-
cially given their relative levels of experience with free div-
ing.

   [6] The prior panel remanded this case “for the limited pur-
pose of having the district court make a finding as to whether
Kahikolu’s failure to provide an operations manual to the
person-in-charge of the Frogman II vessel . . . played any part
in producing the injury, no matter how slight, to Mr. Mac-
Donald.” MacDonald, 442 F.3d at 1200. Although it did not
expressly mention the Pennsylvania Rule, the court did not
require the district court to apply the Rule, and for good rea-
son: regardless of the kinds of claims to which the Rule might
apply, it does not apply here. The district court correctly fol-
lowed our instructions on remand; the judgment below is
        MACDONALD v. KAHIKOLU, LTD.   13157
AFFIRMED.
