¶ 1 The United States Court of Appeals for the Tenth Circuit has certified questions of state law to this Court under the Oklahoma Uniform Certification of Questions of State Law Act, 20 O.S.2001 §§ 1601, et seq. The federal court asks:
1. Is severability analysis required in light of the preemption of [Okla. Const.] article XXIII, § 1A(B)(1), § 1A(C), and § 1A(E) (insofar as it enforces § 1A(B)(1), § 1A(B)(5), and § 1A(C)) as to workers covered by the NLRA, as opposed to the ‘invalidation’ of those provisions?
2. If severability analysis is appropriate, are § 1A(B)(1), § 1A(B)(5), § 1A(C), and § 1A(E) (insofar as it enforces § 1A(B)(1), § 1A(B)(5), and § 1A(C)) sev-erable from the non-preempted portions of § 1A?
We answer “no” to Question 1. Thus, it is unnecessary to answer Question 2.
INTRODUCTION
¶ 2 In September 2001 the people of Oklahoma approved at a special election State Question 695, a referendum submitted to them by a Joint Resolution of the Oklahoma Legislature. Upon its approval by the people, SQ 695 immediately amended the Oklahoma Constitution by adding Art. 23, § 1A.1 *837This new provision is usually either called the “right to work law” or the “right to work amendment.”
¶3 In November 2001, several labor organizations and a pipeline company sued then Oklahoma Governor Frank Keating in the United States District Court for the Eastern District of Oklahoma seeking a declaration that the right to work law was unconstitutional. Later, Oklahomans for Jobs and Justice, a supporter of right to work, and three individual Oklahoma citizens, who are represented by the National Right to Work Legal Defense and Education Foundation, intervened as defendants.
¶4 In the trial court the parties agreed that no discovery would be necessary to resolve the issues and that submission of those issues via cross-motions for summary judgment would be appropriate. The trial court entered an order and final judgment on June 5, 2002, Local 51k, Transport Workers of America, et al. v. Keating, et al., 212 F.Supp.2d 1319 (E.D.Okla.2002). In its order, the trial court rejected the plaintiffs’ contention that the right to work law should be declared invalid because it was substantially preempted by the Supremacy Clause of the United States Constitution, Art. 6, Cl. 2, and also rejected the plaintiffs’ contention that the amendment violated several provisions of the Oklahoma Constitution. Instead, the trial court held, “Plaintiffs’ federal constitutional attack against Oklahoma’s right-to-work law has no merit and must be rejected.”
The trial court declined to exercise supplemental jurisdiction over the remaining state law issues raised by plaintiffs.
¶ 5 The trial court held that the right to work amendment did not apply to employees covered by the Railway Labor Act,2 the Civil Service Reform Act,3 or the Postal Reorganization Act;4 nor did it have any application to federal enclaves, such as military bases. Thus, held the trial court, no preemption issues existed as to employees covered by these federal acts because the Oklahoma right to work amendment itself contemplated that those employees were excluded from the amendment’s ambit.
¶ 6 The trial court held that § 1A(B)(5) of the right to work amendment, relating to exclusive hiring halls,5 conflicted with and was preempted by the Labor Management Relations Act and the National Labor Relations Act, § 14(b), as amended, 29 U.S.C. § 164(b). The trial court also held that § 1A(C) of the right to work amendment, relating to payroll checkoff arrangements, conflicted with and was preempted by the Labor Management Relations Act, 29 U.S.C. § 186(c)(4), which regulates such checkoff arrangements.
¶ 7 After concluding that § 1A(B)(5) and § 1A(C) of the right to work amendment conflict with and are preempted by federal law, the trial court went on to analyze whether, under Oklahoma law, the remaining provisions, primarily § lA(B)(l)-§ 1A(B)(4), were capable of standing alone and being *838executed in accordance with the intent of the people, or were so interdependent with the preempted provisions, it could not be said that the people would have voted to enact the remaining provisions by themselves. The trial court held that the remaining provisions of the right to work amendment, subsections (B)(1)-(B)(4), were “the law’s core provisions banning union and agency shops [and] would have been enacted notwithstanding the absence of the invalid provisions.” 212 F.Supp.2d at 1329.
¶ 8 On appeal the United States Court of Appeals for the Tenth Circuit held that § 1A(B)(1)6 of the right to work amendment was also preempted by federal law. As a result of this holding, the Court of Appeals, on its own motion, submitted to us the certified questions set out above and sought our “authoritative guidance.”
HISTORICAL BACKGROUND
¶ 9 The Oklahoma right to work law is one of many that have been passed throughout the United States through both legislation and constitutional amendment. Such laws were enacted to protect employees against discrimination on account of their membership or nonmembership in labor organizations. The U.S. Supreme Court first'held that such laws weré constitutional in 1949 in the companion cases of Lincoln Federal Labor Union No. 19129, A.F. of L. v. Northwestern Iron & Metal Co., 335 U.S. 525, 69 5.Ct. 251, 93 L.Ed. 212 (1949) and A.F. of L. v. American Sash & Door Co., 335 U.S. 538, 69 S.Ct. 258, 93 L.Ed. 222 (1949). The court held that the Arizona, Nebraska, and North Carolina right to work laws violated neither the due process clause nor the equal protection clause of the 14th Amendment to. the United States Constitution.
¶ 10 In 1947, the congress passed § 14(b) of the Labor Management Relations Act, 29 U.S.C. § 164(b), which specifically authorized states to prohibit agreements between unions and employers requiring membership in a union as a condition of employment. Similarly, § 8 of the same Act, 29 U.S.C. § 158, provided, in effect, that a worker can’t be fired for nonmembership in a union if the worker’s nonmembership results from the worker’s refusal to pay union dues.
¶ 11 The various forms of collective bargaining agreements between unions and employers that require employees to pay union dues in one form or another are generally characterized as “security agreements.” Lincoln Federal, 335 U.S. at 528, 69 S.Ct. at 253. The conflict over right to work laws has arisen because of the opposing attitudes toward security agreements. Right to work advocates believe that every worker should have the right to decline to pay dues to an organization whose views the worker may oppose, but unions believe that no worker should be entitled to benefit from the advantages secured by unions without having contributed to the unions’ support. The cases dealing with this issue are collected and discussed in a recent A.L.R. annotation, Validity, Construction, and Application of State Righh-to-Work Provisions, 105 A.L.R.5th 243 (2003).
DISCUSSION
I.
Severability Analysis is not Required because the right to work law contemplates that some of its provisions might not operate in some limited circumstances as a result of the interpretation of federal law by federal courts.
¶ 12 As noted earlier, the trial court held that Oklahoma’s right to work amendment did not apply to employees covered by the Railway Labor Act, the Civil Service Reform Act, or the Postal Reorganization Act, and had no application to federal enclaves, such as military bases. Thus, the trial court concluded that no preemption issue existed as to employees covered by these federal acts because the Oklahoma right to *839work amendment itself contemplated that those employees were excluded from the amendment’s ambit. For reasons discussed below, we agree with the trial court’s conclusion that the right to work amendment itself contemplated that, because of the operation of federal law, certain employees in certain circumstances might not be covered by the right to work amendment’s terms.
¶ 13 First, we note that whether to apply severability analysis here is a matter of state law. With respect to whether sever-ability analysis is required here, we think it only logical to extend the trial court’s analysis concerning the Railway Labor Act, the Civil Service Reform Act, the Postal Reorganization Act, and federal enclaves to those sections of the right to work amendment that have been held to be preempted by the Labor Management Relations Act and the National Labor Relations Act. Consequently, we hold that the right to work amendment contemplates that certain of its provisions might not operate under certain conditions because of the Labor Management Relations Act and the National Labor Relations Act, just as the trial court held that the right to work amendment contemplated that it would not apply to employees covered by the Railway Labor Act, the Civil Service Reform Act, or the Postal Reorganization Act, and had no application to federal enclaves, such as military bases. Thus, severability analysis is not necessary.
¶ 14 Our conclusion that severability analysis is unnecessary is buttressed by the fact that the Oklahoma right to work law applies to state and local government workers and agricultural workers, regardless of its preemption by federal law with respect to certain classes of employees in certain situations. Plaintiffs argue that this is not important because state employees are currently not subject to security agreements because of legislation. Based on this fact, plaintiffs claim that the right to work law provides no new protections to state workers. But the right to work law is a constitutional amendment, so it will protect state employees from any legislative changes that might otherwise be made to labor laws governing public employees. Thus, the right to work law provides a significant additional protection to public employees.
II.
Constitutional provisions are entitled to the same presumption of validity as legislative provisions.
¶ 15 We have held that it is “the cardinal principle of statutory construction” that a statute is constitutional and should be sustained against challenge where it is possible to do so. In re Application of the Oklahoma Dept. of Transp., 2002 OK 74, ¶ 27, 64 P.3d 546, 553, quoting with approval, NLRB v. Jones & Laughlin Steel Corp., 301 U.S. 1, 57 S.Ct. 615, 81 L.Ed. 893 (1937); and Coyle v. Smith, 1911 OK 64, 113 P. 944, 971. This principle is codified in 75 O.S.2001 § lla(l).7 We hold that this “cardinal principle” applies equally to constitutional provisions as well as to statutory enactments. The Supreme Court of Florida reached the same conclusion in Ray v. Mortham, 742 So.2d 1276, 1281 (Fla.1999). Although the Florida court held that severability analysis was required, contrary to our holding here, it nevertheless held, as have we, that the presumption of constitutionality applies to constitutional provisions as well as to legislation.8 The Florida Supreme Court held:
*840The issue of severability arises only after an amendment already approved by voters has been challenged. Rather than ignoring the results of the election and requiring the Secretary of State to show that voters would have approved an amendment without the unconstitutional provisions, the burden is properly placed on the challenging party. The analysis urged by appellants would be the antithesis of the purpose underlying severability — to preserve the constitutionality of enactments where it is possible to do so. Accordingly, we conclude that we should adopt the severability analysis that we have applied to legislative enactments.
[Emphasis added.] As was the case in Florida, plaintiffs would have us adopt an analysis, which to succeed would require us to ignore the presumption of validity to which the right to work amendment is entitled. This we decline to do.
¶ 16 Plaintiffs’ argument that the people would not have approved the right to work law if they had known that certain of its provisions would not apply because of federal law strikes us as counterintuitive. Why would the people not approve a constitutional change that would protect workers from the involuntary payment of union dues simply because federal courts applying federal law might decide that some of its provisions would not apply to some but not all workers in clearly defined circumstances? We conclude that the possibility that the federal courts might hold that certain employees would not be subject to the right to work law cannot be assumed to be a factor which would haye caused the people to vote against its passage. It is clear, therefore, that plaintiffs have failed in their burden, as defined by In re Application of the Oklahoma Dept. of Transp., 2002 OK 74 at ¶ 27, 64 P.3d 546, to show that the actions of the federal courts in declaring that certain provisions of the amendment are preempted in certain circumstances has, somehow, rendered the right to work law unconstitutional.
¶ 17 It is important to keep in mind that the federal courts in this matter have not declared any provision of the right to work law unconstitutional. Instead, the federal courts have merely held that the right to work law does not apply in certain circumstances due to the primacy of federal law, not that preemption lead to invalidation of any of the right to work law’s provisions. Thus, the cases cited by plaintiffs in which this Court has examined whether a statute containing unconstitutional provisions would have been passed, had the legislature known that part of what it passed was unconstitutional, are inapposite here. See, for example, Comanche Light & Power v. Nix, 1916 OK 330, 156 P. 293, where the U.S. Supreme Court had declared that a state taxation statute was partially unconstitutional because it attempted to regulate interstate commerce. Here, by contrast, the federal courts have held that certain of the right to work law’s terms are preempted by federal law, not that they are unconstitutional. Indeed, the Tenth Circuit carefully spelled out in its certified question .-No. 1 that certain of the right to work law’s provisions were unenforceable because of their “preemption .... as opposed to the ‘invalidation’ of those provisions.” Certified Question No. 1.
¶ 18 Just as whether some of the right to work amendment’s provisions were preempted by federal law was a question of federal law, whether the finding of the federal court’s requires us to engage in severability analysis is a question of state law. We hold that severability analysis is not necessary here for the reason that the right to work law contemplated that some of its provisions might be preempted by federal law and because plaintiffs failed to overcome the presumption that the right to work law is valid and enforceable. Thus, we decline to address ~ plaintiffs’ various 'legal arguments in support of their claim that the rulings of the federal courts in this matter establish that the voters were somehow mislead.
CONCLUSION
¶ 19 Although the question whether state law is preempted is a matter of federal law, the severability question is a matter of state law. Under Oklahoma law, constitu*841tional provisions are entitled to the same presumption of validity as are statutes. We hold that rulings by federal courts applying federal law to the effect that certain provisions of the right to .work law are subject to preemption (but not “invalidation”) of some of its terms as to some but not all workers in some but not all situations fails to overcome the presumption of validity to which the right to work law is entitled under Oklahoma law. Severability analysis is therefore not called for here. Further, to hold the right to work amendment unconstitutional under the circumstances presented here would be to thwart the clearly expressed will of the people.
CERTIFIED QUESTIONS ANSWERED.
WATT, C.J., OPALA, V.C.J., HODGES, HARGRAVE, KAUGER, WINCHESTER, JJ., concur. LAVENDER, SUMMERS, BOUDREAU, JJ., concur in result.. That amendment, Okla. Const., Art. 23, § 1A provides:
§ 1A. Participation in labor organization as condition of employment prohibited
A. As used in this section, "labor organization” means any organization of any kind, or agency or employee representation committee or union, that exists for the purpose, in whole or in part, of dealing with employers concerning wages, rates of pay, hours of work, other conditions of employment, or other forms of compensation.
B. No person shall be required, as a condition of employment or continuation of employment, to:
*8371. Resign or refrain from voluntary membership in, voluntary affiliation with, or voluntary financial support of a labor organization;
2. Become or remain a member of a labor organization;
3. Pay any dues, fees, assessments, or other charges of any kind or amount to a labor organization;
4. Pay to any charity or other third party, in lieu of such payments, any amount equivalent to or pro rata portion of dues, fees, assessments, or other charges regularly required of members of a labor organization; or
5. Be recommended, approved, referred, or cleared by or through a labor organization.
C.It shall be unlawful to deduct from the wages, earnings, or compensation of an employee any union dues, fees, assessments, or other charges to be held for, transferred to, or paid over to a labor organization unless the employee has first authorized such deduction.
D. The provisions of this section shall apply to all employment contracts entered into after the effective date of this section and shall apply to any renewal or extension of any existing contract.
E. Any person who directly or indirectly violates any provision of this section shall be guilty of a misdemeanor.
. 45 U.S.C. §§ 151, etseq.
. 5 U.S.C. §§ 7101, etseq.
. 39 U.S.C. §§ 1201, etseq.
. A "hiring hall" agreement is one in which the employer agrees to hire only workers the union approves.
. Section 1A(B)(1) of the right to work amendment provides:
B. No person shall be required, as a condition of employment or continuation of employment, to:
1. Resign or refrain from voluntary membership in, voluntary affiliation with, or voluntary financial support of a labor organization
. Title 75 O.S.2001 § lla(l) provides:
In the construction of the statutes of this state, the following rules shall be observed:
1. For any act enacted on or after July 1, 1989, unless there is a provision in the act that the act or any portion thereof or the application of the act shall not be severable, the provisions of every act or application of the act shall be severable. If any provision or application of the act is found to be unconstitutional and void, the remaining provisions or applications of the act shall remain valid, unless the court finds:
a. the valid provisions or application of the act are so essentially and inseparably connected with, and so dependent upon, the void provisions that the court cannot presume the Legislature would have enacted the remaining valid provisions without the void one; or
b. the remaining valid provisions or applications of the act, standing alone, are incomplete and are incapable of being executed in accordance with the legislative intent. '
. We note that severability analysis was called for in the Florida case because a portion of the constitutional amendment at issue there, a term limits provision, was clearly unconstitutional to the extent that it purported to limit the terms of *840Unites States Congressmen and Senators, which ís a situation that does not obtain here.