delivered the opinion of the Court.
This action involves the scope of federal pre-emption under the Railway Labor Act (RLA), 45 U. S. C. § 151 et seq. The RLA, which was extended in 1936 to cover the airline industry, see Act of Apr. 10, 1936, ch. 166, 49 Stat. 1189; 45 U. S. C. §§ 181-188, sets up a mandatory arbitral mechanism to handle disputes “growing out of grievances or out of the interpretation or application of agreements concerning rates of pay, rules, or working conditions,” 45 U. S. C. § 153 First (i). The question in this case is whether an aircraft mechanic who claims that he was discharged for refusing to certify the safety of a plane that he considered unsafe and for reporting his safety concerns to the Federal Aviation Administration may pursue available state-law remedies for wrongful discharge, or whether he may seek redress only through the RLA’s arbitral mechanism. We hold that the RLA does not pre-empt his state-law causes of action.
I
' Respondent Grant Norris is an aircraft mechanic licensed by the Federal Aviation Administration (FAA). His aircraft mechanic’s license authorizes him to approve an airplane and *249 return it to service after he has made, supervised, or inspected certain repairs performed on that plane. See Certification: Airmen Other Than Flight Crewmembers, 14 CFR §§ 65.85 and 65.87 (1987). If he were to approve any aircraft on which the repairs did not conform to FAA safety regulations, the FAA could suspend or revoke his license. See Maintenance, Preventive Maintenance, Rebuilding and Alteration, 14 CFR §43.12 (1992).
On February 2, 1987, respondent was hired by petitioner Hawaiian Airlines, Inc. (HAL). Many of the terms of his employment were governed by a collective-bargaining agreement (CBA) negotiated between the carrier and the International Association of Machinists and Aerospace Workers. Under the CBA, respondent’s duties included inspecting and repairing all parts of a plane and its engine. On July 15, 1987, during a routine preflight inspection of a DC-9 plane, he noticed that one of the tires was worn. When he removed the wheel, respondent discovered that the axle sleeve, which should have been mirror smooth, wаs scarred and grooved. This damaged sleeve could cause the landing gear to fail. Respondent recommended that the sleeve be replaced, but his supervisor ordered that it be sanded and returned to the plane. This was done, and the plane flew as scheduled. At the end of the shift, respondent refused to sign the maintenance record to certify that the repair had been performed satisfactorily and that the airplane was fit to fly. See 14 CFR § 43.9(a) (1992). The supervisor immediately suspended him pending a termination hearing. Respondent immediately went home and called the FAA to report the problem with the sleeve. 1
Respondent then invoked the grievanсe procedure outlined in the CBA, and a “Step 1” grievance hearing was held *250 on July 31, 1987. Petitioner HAL accused respondent of insubordination, claiming that his refusal to sign the record violated the CBA’s provision that an aircraft mechanic “may be required to sign work records in connection with the work he performs.” Respondent relied on the CBA’s guarantees that an employee may not be discharged without just cause and may not be disciplined for refusing to perform work that is in violation of health or safety laws. The hearing officer terminated respondent for insubordination.
Still conforming to the CBA procedures, respondent appealed his termination, seeking a “Steр 3” grievance hearing. Before this hearing took place, HAL offered to reduce respondent’s punishment to suspension without pay, but warned him that “any further instance of failure to perform [his] duties in a responsible manner” could result in discharge. Respondent did not respond to this offer, nor, apparently, did he take further steps to pursue his grievance through the CBA procedures.
On December 18, 1987, respondent filed suit against HAL in Hawaii Circuit Court. His complaint included two wrongful-discharge torts — discharge in violation of the public policy expressed in the Federal Aviation Act of 1958 and implementing regulations, and discharge in violation of Hawaii’s Whistleblower Protection Act, Haw. Rev. Stat. §§ 378-61 to 378-69 (1988). 2 He also alleged that HAL had breached the CBA. HAL removed the action to the United States District Court for the District of Hawaii, which dismissed the breach-of-contract claim as pre-empted by the *251 RLA, and remanded the other claims to the state trial court. The trial court then dismissed respondent’s claim of discharge in violation of public policy, holding that it, too, was pre-empted by the RLA’s provision of exclusive arbitral procedures. The state court certified its order as final to permit respondent to take an immediate appeal.
In the meantime, respondent had filed a second lawsuit in state court, naming as defendants three of HAL’s officеrs who allegedly directed, confirmed, or ratified the claimed retaliatory discharge. 3 He again sought relief for, among other things, discharge in violation of public policy and of the Hawaii Whistleblower Protection Act. The Hawaii trial court dismissed these two counts as pre-empted by the RLA and certified the case for immediate appeal.
The Supreme Court of Hawaii reversed in both cases, concluding that the RLA did not pre-empt respondent’s state tort actions.
Norris
v.
Hawaiian Airlines, Inc.,
We granted certiorari in these consolidated cases,
II
A
Whether federal law pre-empts a state law establishing a cause of action is a question of congressional intent. See
Allis-Chalmers Corp.
v.
Lueck,
Congress’ purpose in passing the RLA was to promote stability in labor-management relations by providing a comprehensive framework for resolving labor disputes.
Atchison, T.& S. F. R. Co.
v.
Buell,
Petitioners contend that the conflict over respondent’s firing is a minor dispute. If so, it must be resolved only through the RLA mechanisms, including the carrier’s internal dispute-resolution processes and an adjustment board established by the employer and the unions. See 45 U. S. C. § 184;
Buell,
B
The Court’s inquiry into the scope of minor disputes begins, of course, with the text of the statute. Petitioners point out that the statute defines minor disputes to include “disputes . . . growing out of grievances,
or
out of the interpretation or application of [CBA’s].” Petitioners argue that this disjunctive language must indicate that “grievances” means something other than labor-contract disputes, else the term “grievances” would be superfluous. Accordingly, petitioners suggest that “grievances” should be read to mean all employment-related disputes, including those based on statutory or common law. Evén if we were persuaded that the word “or” carried this weight, but cf.
United States
v.
Olano,
We think it more likely that “grievances,” like disputes over “the interpretation or application” of CBA’s, refers to disagreements over how to give effect to the bargained-for agreement. The use of “grievance” to refer to a claim arising out of a CBA is common in the labor-law context in general, see,
e. g., Paperworkers
v.
Misco, Inc.,
Accordingly, we believe that the most natural reading of the term “grievances” in this context is as a synonym for disputes involving the application or interpretation of a CBA. See Webster’s Third New International Dictionary 1585 (1986) (the word “or” may be used to indicate “the synonymous, equivalent, or substitutive character of two words or phrases”). Nothing in the legislative history of the RLA 4 or other sections of the statute 5 undermines this conclusion. But even accepting that § 151a is susceptible of more than one interpretation, no proposed interpretation demonstrates a clear and manifest congressional purpose to create a regime *256 that broadly pre-empts substantive protections extended by the States, independent of any negotiated labor agreement.
C
Our case law confirms that the category of minor disputes contemplated by § 151a are those thаt are grounded in the CBA. We have defined minor disputes as those involving the interpretation or application of existing labor agreements. See,
e. g., Conrail,
Moreover, we have held that the RLA’s mechanism for resolving minor disputes does not pre-empt causes of action to enforce rights that are independent of the CBA. More than 60 years ago, the Court rejected a railroad’s argument that the existence of the RLA arbitration scheme preempted a state statute regulating the number of workers required to operate certain equipment.
Missouri Pacific R. Co.
v.
Norwood,
“State laws have long regulated a great variety of conditions in transportation and industry, such as sanitary facilities and conditions, safety devices and protections, purity of water supply, fire protection, and innumerable others. Any of these matters might, we suppose, be the subject of a demand by work[ers] for better protection and upon refusal might be the subject of a labor dispute which would have such effect on interstate commerce that federal agencies might be invoked to deal with some phase of it. . . . But it cannot be said that the minimum requirements laid down by state authority are all set aside. We hold that the enactment by Congress of the [RLA] was not a preemption of the field of regulating working conditions themselves ....” Id., at 6-7.
Thus, under Norwood, substantive protections provided by state law, independent of whatever labor agreement might govern, are not pre-empted under the RLA.
Although
Norwood
and
Terminal Railroad
involved state workplace safety laws, the Court has taken a consistent approach in the context of state actions for wrongful discharge. In
Andrews
v.
Louisville & Nashville R. Co.,
“Here it is conceded by all that the only source of [Andrews’] right not to be discharged, and therefore to treat an alleged discharge as a ‘wrongful’ one that entitles him *258 to damages, is the [CBA]____[T]he disagreement turns on the extent of [the railroad’s] obligation to restore [Andrews] to his regular duties following injury in an automobile accident. The existence and extent of such an obligation in a case such as this will depend on the interpretation of the [CBA]. Thus [Andrews’] claim, and [the railroad’s] disallowanсe of it, stem from differing interpretations of the [CBA]. . . . His claim is therefore subject to the Act’s requirement that it be submitted to the Board for adjustment.” Id., at 324 (emphasis added).
Here, in contrast, the CBA is not the “only source” of respondent’s right not to be discharged wrongfully. In fact, the “only source” of the right respondent asserts in this action is state tort law. Wholly apart from any provision of the CBA, petitioners had a state-law obligation not to fire respondent in violation of public policy or in retaliation for whistle-blowing. The parties’ obligation under the RLA to arbitrate disputes arising out of the application or interpretation of the CBA did not relieve petitioners of this duty.
Atchison, T. & S. F. R. Co.
v.
Buell,
“The fact that an injury otherwise compensable under the FELA was caused by conduct that may have been *259 subject to arbitratiоn under the RLA does not deprive an employee of his opportunity to bring an FELA action for damages. . .. The FELA not only provides railroad workers with substantive protection against negligent conduct that is independent of the employer’s obligations under its collective-bargaining agreement, but also affords injured workers a remedy suited to their needs, unlike the limited relief that seems to be available through the Adjustment Board. It is inconceivable that Congress intended that a worker who suffered a disabling injury would be denied recovery under the FELA simply because he might also be able to process a narrow labor grievance under the RLA to a successful conclusion.”480 U. S., at 564-565 .
It likened
Buell
to othеr cases in which the Court had concluded that “notwithstanding the strong policies encouraging arbitration, ‘different considerations apply where the employee’s claim is based on rights arising out of a statute designed to provide minimum substantive guarantees to individual workers,’”
id.,
at 565, quoting
Barrentine
v.
Arkansas-Best Freight System, Inc.,
*260 D
The pre-emption standard that emerges from the line of cases leading to
Buell
— that a state-law cause of action is not pre-empted by the RLA if it involves rights and obligations that exist independent of the CBA — is virtually identical to the pre-emption standard the Court employs in cases involving § 301 of the LMRA, 29 U. S. C. § 185.
7
In
Allis-Chalmers Corp.
v.
Lueck,
It cautioned, however, that other state-law rights, those that existed independent of the contract, would not be similarly pre-empted:
“Of course, not every dispute concerning employment, or tangentially involving a provision of a collective-bargaining agreement, is pre-empted by §301 or other provisions of the federal labor law. ... Nor is there any suggestion that Congress, in adopting §301, wished to give the substantive provisions of private agreements the force of federal law, ousting any inconsistent state regulation.... Clearly, § 301 does not grant the parties to a collective-bargaining agreement the ability to contract for what is illegal under state law. In extending the pre-emptive effect of §301 beyond suits for breach *261 of contract, it would be inconsistent with congressional intent under that section to pre-empt state rules that proscribe conduct, or establish rights and obligations, independent of a labor contract.” Id., at 211-212. 8
In a case remarkably similar to the case before us now, this Court made clear that the existence of a potential CBA-based remedy did not deprive an employee of independent remedies available under state law. In
Lingle
v.
Norge Div. of Magic Chef, Inc.,
It recognized that where the resolution of a state-law claim depends on an interpretation of the CBA, the claim is preempted.
Id.,
at 405-406, citing
Lueck, supra; Teamsters
v.
Lucas Flour Co.,
While recognizing that “the state-law analysis might well involve attention to the same factual considerations as the contractual determination of whether Lingle was fired for just cause,” id., at 408, the Court disagreed that
“such parallelism rendered] the state-law analysis dependent upon the contractual analysis. For while there may be instances in which the National Labor Relations Act pre-empts state law on the basis of the subject matter of the law in question, § 301 pre-emption merely ensures that federal law will be the basis for interpreting collective-bargaining agreements, and says nothing about the substantive rights a State may provide to workers when adjudication of those rights does not depend upon the interpretation of such agreements. In other words, even if dispute resolution pursuant to a collective-bargaining agreement, on the one hand, and state law, on the other, would require addressing precisely the same set of facts, as long as the state-law claim can be resolved without interpreting the agreement itself, the claim is ‘independent’ of the agreement for §301 pre-emption purposes.” Id., at 408-410.
The Court’s ruling in
Lingle
that the LMRA pre-empts state law only if a state-law claim is dependent on the interpretation of a CBA is fully consistent with the holding in
Buell,
E
In reaching this conclusion, we reject petitioners’ suggestion that this contract-dependent standard for minor dis
*264
putes is inconsistent with two of our prior cases,
Elgin, J & E. R. Co.
v.
Burley,
This language is sweeping, but its effect is limited. The conflict in Burley, which the parties agreed was a minor dispute, concerned the terms of a CBA, and not some other “incident of the employment relationship,” or any “omitted case.” These references, therefore, are dicta. Moreover, even the “omitted case” dictum logically can refer to a norm that the parties have created but have omitted from the CBA’s explicit language, rathеr than to a norm established by a legislature or a court. 10 Finally, Burley’s one specific example of an “omitted case” — claims for personal injury that do not depend on the contract — was found in Buell to be outside the RLA’s exclusive jurisdiction. Nonetheless, to avoid any confusion, we expressly disavow any language in *265 Burley suggesting that minor disputes encompass state-law claims that exist independent of the CBA.
Conrail,
like
Burley,
involved no pre-emption analysis. The parties agreed that the dispute — a workers’ challenge to the railroad’s drug-testing policies — was governed by the RLA, because Conrail’s policy of conducting physical examinations was an implied term of the CBA.
Petitioners, however, pin their hopes on the observation that “[w]here an employer asserts a contractual right to take the contested action, the ensuing dispute is minor if the action is
arguably justified
by the terms of the parties’ collective-bargaining agreement.”
Ill
Returning to the action before us, the question under
Lingle
is whether respondent’s state-law wrongful-discharge claims are independent of the CBA. Petitioners argue that resort to the CBA is necessary to dеtermine whether respondent, in fact, was discharged. This argument is foreclosed by
Lingle
itself.
Lingle
teaches that the issue to be decided in this action — whether the employer’s actions make out the element of discharge under Hawaii law — is a “purely factual questio[n].”
Nor are we persuaded by petitioners’ contention that the state tort claims require a determination whether the discharge, if any, was justified by respondent’s failure to sign the maintenance record, as the CBA required him to do. Although such a determination would be required with regard to respondent's separate allegation of discharge in violation of the CBA, the District Court dismissed that count as preempted by the RLA, and rеspondent does not challenge that dismissal. The state tort claims, by contrast, require only the purely factual inquiry into any retaliatory motive of the employer.
Accordingly, we agree with the Supreme Court of Hawaii that respondent’s claims for discharge in violation of public policy and in violation of the Hawaii Whistleblower Protection Act are not pre-empted.by the RLA, and we affirm that court’s judgment.
It is so ordered.
Notes
In response, the FAA initiated a comprehensive investigation, proposed a civil penalty of $964,000 against HAL, proposed the revocation of the license of the supervisor who terminated respondent, and ultimately settled all charges for a substantial fine.
The Hawaii Whistleblower Protection Act forbids an employer to “discharge, threaten, or otherwise discriminate against an employee . . . because . . . [t]he employee . . . reports or is about to report to a public body ... a violation or a suspected violation of a law or rule adopted pursuant to law of this State, a political subdivision of this State, or the United States, unless the employee knows that the report is false.” § 378-62(1). The Act authorizes an employee to file a civil action seeking injunctive relief and actual damages. §378-63(a).
These managerial officers, petitioners here, are Paul J. Finazzo, Howard E. Ogden, and Hatsuо Honma.
During the debates surrounding the RLA’s enactment in 1926, floor statements that, in isolation, could support a broader interpretation of “grievances” were counterbalanced by other statements — some even by the same legislators — that equated grievances with contract interpretation. Compare 67 Cong. Rec. 4517, 8807 (1926), with id., at 4510, 8808. This inconclusive debate hardly calls for fashioning a broad rule of preemption. Moreover, in 1934 when Congress amended the RLA to make arbitration mandatory for minor disputes, the accompanying House Report stated that the bill was intended “to provide sufficient and effective means for the settlement of minor disputes known as ‘grievanсes,’ which develop from the interpretation and/or application of the contracts between the labor unions and the carriers, fixing wages and working conditions.” H. R. Rep. No. 1944, 73d Cong., 2d Sess., 2-3 (1934).
Petitioners cite the statute’s reference to the parties’ general duties as including “settl[ing] all disputes, whether arising out of the application of [collective bargaining] agreements or otherwise.” 45 U. S. C. § 152 First. This provision, which is phrased more broadly than the operative language of § 153 Frst (i), does not clearly refer only to minor disputes. But even if this provision is read to require parties to try to settle certain issues arising out of the employment relationship but not specifically addressed by the CBA, this does not compel the conclusion that all issues touching on the employment relationship must be resolved through arbitration or that all claims involving rights and duties that exist independent of the CBA are thereby pre-empted. Our precedents squarely reject this pervasive pre-emption.
Buell,
of course, involved possible RLA preclusion of a cause of action arising out of
& federal
statute, while this case involves RLA pre-emption of a cause of action arising out of
state
law and existing entirely independent of the CBA. That distinction does not rob
Buell
of its force in this context. See
Lingle
v.
Norge Div. of Magic Chef, Inc.,
Section 301(a) provides federal-court jurisdiction over controversies involving CBA’s and “authorizes federal courts to fashion a body of federal lav? for the enforcement of these collective bargaining agreements.”
Textile Workers
v.
Lincoln Mills of Ala.,
The Court applies these principles in
Livadas
v.
Bradshaw,
in which we reject the claim that an employee’s state-law right to receive a penalty payment from her employer was pre-empted under §301 bеcause the penalty was pegged to her wages, which were determined by the governing CBA. The Court states that “when the meaning of contract terms is not the subject of dispute, the bare fact that a collective-bargaining agreement will be consulted in the course of state-law litigation plainly does not require the claim to be extinguished.”
Ante,
at 124, citing
Lingle
v.
Norge Div. of Magic Chef, Inc.,
It is true, as petitioners observe, that the RLA and the LMRA are not identical in language, history, and purpose. The LMRA, unlike the RLA, does not mandate arbitration, nor does it prescribe the types of disputes to be submitted to arbitration under bargaining agreements. Nonetheless, the common purposes of the two statutes, the parallel development of RLA and LMRA pre-emption law, see,
e. g., Machinists
v.
Central Airlines, Inc.,
Lower courts, too, have recognized the appropriateness of the
Lingle
standard to RLA pre-emption analysis. See,
e. g., Anderson
v.
American Airlines, Inc.,
See
Detroit & Toledo Shore Line R. Co.
v.
Transportation Union,