concurring in result and joined by LAVENDER, J. and BOUDREAU, J.
¶ 1 The federal courts in this case have determined that the Oklahoma Right to Work amendment, Okla. Court Art. 23 § 1A, has no application to certain employees,1 and further was preempted in part by certain federal legislation.2 The Federal District Court held that even with the invalid and preempted portions out, the Right to Work amendment’s core provisions would have still been enacted, and thus withstood judicial severability analysis.
¶ 2 Preemption questions are those of federal law3 and are not before us today. But severability of a partially invalid set of laws is a state question.4 I must initially point out that the Court’s opinion distinguishing preempted state law from unconstitutionality is incorrect. A state law is unconstitutional when it is preempted by federal legislation. Because the Court’s opinion turns on this point, I must point out that the U.S. Supreme Court does not share our Court’s view. For example:
Because the state Act’s provisions conflict with Congress’s specific delegation to the President of flexible discretion, with limitation of sanctions to a limited scope of actions and actors, and with direction to develop a comprehensive, multilateral strategy under the federal Act, it is preempted, and its application is unconstitutional, under the Supremacy Clause.
Crosby v. National Foreign Trade Council, 530 U.S. 363, 388, 120 S.Ct. 2288, 147 L.Ed.2d 352 (2000), (emphasis added).
One hornbook explains: “The supremacy clause mandates that federal law overrides,' i.e., preempts, any state regulation where there is an actual conflict between the two sets of legislation.” J. Nowak & R. Rotunda, Constitutional Law, 319 (5th Ed.1995). Preempted state law is struck down as unconstitutional — it violates the supremacy clause of the U.S. Constitution.5 In Crosby, *847the application was unconstitutional, as in the present case before us. It is the partial application of state law that is preempted and thus unconstitutional.6
¶ 3 On appeal the Tenth Circuit Court has certified to us the following questions:
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)) severable from the non-preempted portions of § 1A?
¶4 The first question: “Is a severability analysis required?” I would answer in the affirmative. However, the Court states that it takes the reasoning applicable to those workers covered by the Railway Labor Act, Civil Service Reform Act, and Postal Reorganization Act, and applies it to workers covered by the National Labor Relations Act and the Labor Management Relations Act. Opin. at ¶ 13. I do not agree with this analysis in part, because: (1) The federal court stated that Art. 23 § 1A was not applicable in its entirety to workers covered by Railway Labor Act, Civil Service Reform Act, and Postal Reorganization Act, and that only portions of Art. 23 § 1A were invalid as to workers covered by the National Labor Relations Act and the Labor Management Relations Act; and (2) The point of the certified questions is whether valid portions (i.e., non-preempted portions) of Art. 23 § 1A may nevertheless apply to workers covered by the National Labor Relations Act and the Labor Management Relations Act.7
¶ 5 The Court concludes that the valid portions of Art. 23 § 1A apply to all workers to whatever extent they are not preempted. I agree in that result here, but only because of a severability analysis showing that the remaining portions of Art. 23 § 1A are capable of being enforced absent the preempted language. The severability analysis is what shows this capability.
¶ 6 Although the Court’s opinion states that a severability analysis is not necessary, I must note that some of the language used by the Court herein is part of a severability analysis used by most courts. For example, the Court’s opinion states that a severability analysis is not needed because Art. 23 § 1A was not intended to apply to certain groups of people, i.e., those covered by the Railway Labor Act, Civil Service Reform Act, Postal Reorganization Act. As I explain below, this type of reasoning, non-application of a state law to a particular class, or here, easily identifiable groups of people, is part of a sever-ability analysis.
¶ 7 Cases involving a preemption of state law by federal law frequently involve a sever-ability analysis, and the question of whether the remaining portions of non-preempted state law may remain valid presents a question for a state court to decide. For example in one opinion the High Court explained that a state’s law was, as in the case before us today, preempted by federal law, in part,8 and the Court concluded that the proper state court should decide whether the remaining valid provisions of state law were severable.
State legislation is invalid “to the extent that it actually conflicts with federal law,” *848Pacific Gas & Electric Co. v. Energy Resources Comm’n, 461 U.S. 190, 204, 103 S.Ct. 1713, 1722, 75 L.Ed.2d 752 (1983), and such a conflict has been demonstrated in this case. We leave to the New Jersey Supreme Court the state-law question whether, or to what extent, the nonpre-empted provisions of the statute are sever-able from the pre-empted provisions.
Exxon Corp. v. Hunt, 475 U.S. 355, 376, 106 S.Ct. 1103, 89 L.Ed.2d 364 (1986).
This Court has used a severability analysis and concluded that invalid language invalidated the entire provision in which the invalid language appeared.9 We have also used a severability analysis for severing the invalid portion and upholding the valid portion as legally effective.10
¶ 8 The severability analysis includes both a facial challenge to the language used in a statute or constitutional provision as well its applications. One author explained the authority on this issue as follows:
“... the Supreme Court, the state courts, and secondary authorities all appear to agree that the invalidity of part of a law or of some of its applications will not affect the remainder (1) if the valid provisions or applications are capable of being given legal effect standing alone, and (2) if the legislature would have intended them to stand with the invalid provisions stricken out.”
Stern, Separability and Separability Clauses in the Supreme Court, 51 Harv. L.Rev. 76 (1937), emphasis added.
That author further explained that courts use a severability analysis for problems of language as well as application
Questions of separability fall into two ■general classes. One relates to situations in which some applications of the same language in a statute are valid and other applications invalid; the other to statutes containing particular language — whether words, phrases, sentences or sections— which is invalid, and other language entirely constitutional.... The fúst will be described as the problem of separable applications; the second as the problem of separable language.
Id. 51 Harv. L.Rev. 78-79 (1937), emphasis in original and material omitted.
This view is consistent with our statute on severability. See, for example, Ethics Commission v. Cullison, 1993 OK 37, 850 P.2d 1069, 1078, where we said that: “Section 11a of Title 75 also requires examining whether an act may be severable in application.”
■ ¶ 9 The method a court uses in making its conclusion is based upon the court’s assessment that the valid portion is capable of being enforced absent the invalid part, and that the legislative body intended such. For example, one author explained that a separability analysis involving different applications of a statute requires a court to determine legislative intent — specifically whether “it is evident, from a contemplation of the statute and of the purpose to be accomplished by it, that it would not have been passed at all, except as an entirety, and that the general purpose of the legislature will be defeated if it shall be held valid as some cases and void as to others.” 1 T. Cooley, Constitutional Limitations, 367 (8th ed.1927). The invalid parts of a legislative act, whether invalid by language or application, must be separable from the valid parts *849so that the valid may be enforced, otherwise the whole act is invalid: “In general where the different portions of the statute form ‘inseparable parts of the same system,’ the whole is invalidated by the unconstitutionality of a part.” T. Sedgwick, The Interpretation and Construction of Statutory and Constitutional Law, 414 (2d ed. 1874). In sum, the U.S. Supreme Court, this Court and authors such as Stern, Cooley, and Sedgwick, agree that a severability analysis is used to determine whether a law, invalid in part, may nevertheless have its valid parts enforced. Thus, I decline to join the Court’s opinion rejecting the application of such analysis to the present controversy.
¶ 10 What did the People intend when Art. 23 § 1A became law? A severability analysis attempts to determine such intent. The challenge to Art. 23 § 1A based upon application to workers covered by the Railway Labor Act, Civil Service Reform Act, Postal Reorganization Act, and the National Labor Relations Act is based solely upon the general and broad nature of the language in Article 23.11 No language in Art. 23 § 1A specifically targets such employees or makes reference to federal law.
¶ 11 In 1996 this Court stated that: “Four years ago, this Court held that the people’s legislative power as defined in article 5, section 1, of the Oklahoma Constitution does not include the power to use the initiative process to attempt to change federal constitutional law.” In re Initiative Petition No. 361, 1996 OK 129, 930 P.2d 186, 195, citing, In re Petition No. 319, State Question No. 612, 1992 OK 122, 838 P.2d 1. No language in Article 23 § 1A may be reasonably construed as an attempt to overturn federal law. These two opinions stating the People’s inability to amend federal law via a State Question predate the passage of Art. 23 § 1, and this Court may presume that the People, acting as a legislative body, were aware of such authority.12 Further, It is nothing unique to the jurisprudence of this State that federal law may be used to carve out an exception to applying an Oklahoma legislative act to certain groups of people. See, e.g., Oklahoma Tax Commission v. Chickasaw Nation, 515 U.S. 450, 458-459, 115 S.Ct. 2214, 132 L.Ed.2d 400 (1995), (Court noted its holdings where it has held unenforceable a number of state taxes whose legal incidence rested on a tribe or on tribal members inside Indian country).
¶ 12 This Court has construed, when possible, statutes and constitutional provisions so as to give effect to valid parts thereof.13 We have said that, as a matter of statutory interpretation, a reasonable and rational statutory construction that upholds the validity of a legislative act will be used by courts. TXO Production Corp. v. Oklahoma Corp. Commission, 1992 OK 39, 829 P.2d 964, 968—969.14 The People’s intent to have a partial *850application of law combined with an absence of any showing of an intent to subvert federal law supports a conclusion of an intent that the valid portions of Article 23 § 1 should be applied as severed.
¶ 13 On this issue'the parties discuss the lack of a severability clause, and the application of 75 O.S. § 11a.15 Section 11a is a statutorily required presumption of sever-ability. Facially, this section applies to “statutes”. Whether § 11a applies does not matter in this constitution-based controversy.16 This is because the absence of a severability clause in Art. 23 § 1A, is not determinative.
¶ 14 When construing a federal statute the U.S. Supreme Court has stated that while the presence of a severability clause shows Congress’ intent for severance, the absence of the clause does not carry with it a showing of an opposite intent.
The inquiry is eased when Congress has explicitly provided for severance by including a severability clause in the statute. This Court has held that the inclusion of such a clause creates a presumption that Congress did not intend the validity of the statute in question to depend on the validity of the constitutionally offensive provision. See INS v. Chadha, 462 U.S. at 932, 103 S.Ct. at 2774; Champlin Refining Co. v. Corporation Comm’n of Oklahoma, 286 U.S. at 235, 52 S.Ct. at 565. In such a case, unless there is strong evidence that Congress intended otherwise, the objectionable provision can be excised from the remainder of the statute. In the absence of a severability clause, however, Congress’ silence is just that — silence—and does not raise a presumption against sev-erability.
Alaska Airlines, Inc. v. Brock, 480 U.S. 678, 686, 107 S.Ct. 1476, 94 L.Ed.2d 661 (1987). Mere legislative silence on the issue of sever-ability may not control the presumption that legislative acts will be enforced to the extent that they are valid.
¶ 15 Part of examining legislative intent is whether the statute, or in this ease a constitutional provision, is capable of being enforced without the offending applications. May the valid language be applied to workers not subject to the invalid portions? In our case today, after the invalid portions are removed as to certain workers, Art 23 § 1A states, in part, that:
No person shall be required, as a condition of employment or continuation of employment, to:
Become or remain a member of a labor organization;
Pay any dues, fees, assessments, or other charges of any kind or amount to a labor organization;
*851Pay 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;
Further, that any person who directly or indirectly violates these provisions shall be guilty of a misdemeanor. These provisions are capable of being enforced, as a matter of state law, apart from the preempted language.
¶ 16 In Potter v. State, 1973 OK CR 228, 509 P.2d 933, our Court of Criminal Appeals discussed a criminal obscenity statute that created an exemption for certain conduct, specifically, “motion pictures produced or manufactured as commercial motion pictures which (1) have the seal under the Production Code of the Motion Picture Association of America, Inc.,” and certain foreign films. Id. 509 P.2d at 934. The court determined that the exemption was both invalid and severable from the remainder of the statute. Id. 509 P.2d at 935-936.17 Similarly, we have discussed whether invalid and valid provisions “are so interwoven as to be incapable of distinct separation.” Parwal Inv. Co. v. State, 1918 OK 498, 175 P. 514, 515.
¶ 17 In our case today, Article 23 § 1A defines certain conduct as constituting a misdemeanor. Similar to Potter, the conduct which is preempted does not interfere with enforcing the remainder of the non-preempted portion of Art. 23 § 1A that defines certain other conduct. The provisions listing types of conduct are not so interwoven as to be incapable of distinct separation. Parwal Inv. Co. v. State, supra.
¶ 18 This Court has indicated that the intent of a legislative body is for its enactments to be enforced in part, unless either a contrary intent is apparent, or the provisions are not capable of separate enforcement. No party has shown an intent of the People that Art. 23 § 1A should not be enforced, at least in part. The non-preempted language of Art. 23 § 1A is capable of being enforced apart from the preempted language.
¶ 19 I would thus answer the two questions in the affirmative. Yes, a severability analysis is required. Yes, the preempted portions are severable from the non-preempted portions. I concur in the Court’s result. The non-preempted parts of the Right To Work Amendment are the law of Oklahoma.
. The Railway Labor Act, 45 U.S.C. § 151 et seq., the Civil Service Reform act, 5 U.S.C. § 7101 et seq., the Postal Reorganization Act, 39 U.S.C. § 1201 et seq.; employees on federal enclaves, such as military bases.
. The Labor Management Relations Act, 29 U.S.C. § 186(c)(4) and the National Labor Relations Act. 29 U.S.C. § 164(b).
. Allis-Chalmers Corp. v. Lueck, 471 U.S. 202, 214, 105 S.Ct. 1904, 85 L.Ed.2d 206 (1985), ("the question whether the Wisconsin tort is sufficiently independent of federal contract inlerpre-tation to avoid pre-emption is, of course, a question of federal law”).
. Exxon Corp. v. Hunt, 475 U.S. 355, 376, 106 S.Ct. 1103, 89 L.Ed.2d 364 (1986), (in the context of a preemption analysis the High Court explained that the proper state court should decide whether state law provisions were severa-ble).
. Article VI of the U.S. Constitution provides that the laws of the United States "shall be the supreme Law of the Land; ... any Thing in the Constitution or Laws of any state to the Contrary notwithstanding.” Art. VI, cl.2.
.One aspect of unconstitutionality, a "void” state law, is seen in those opinions discussing the effect of this federal constitutional supremacy. For example: "It is basic to this constitutional command that all conflicting state provisions be without effect.... Of course, a state statute is void to the extent it conflicts with a federal statute....” Maryland v. Louisiana, 451 U.S. 725, 746-747, 101 S.Ct. 2114, 68 L.Ed.2d 576 (1981), material omitted and emphasis added.
. As I explain herein, I agree with the Court that the People had no intent to subvert federal law when enacting Article 23 § 1A, and that this lack of intent applies equally to all of the federal acts discussed in this proceeding.
. The Court concluded that the New Jersey Spill Compensation and Control Act, N.J.Stal.Ann. §§ 58:10-23.11 to 58:10-23.11z (West 1982 and Supp.1985) (Spill Act), was pre-empted in part. Exxon Corp. v. Hunt, 475 U.S. at 358, 363, 376-377, 106 S.Ct. 1103.
. See, e.g., City of Oklahoma City v. State ex rel. Oklahoma Dept. of Labor, 1995 OK 107, 918 P.2d 26, 31, (an entire act was unconstitutional regardless of a severability clause therein); Ethics Commission v. Cullison, 1993 OK 37, ¶¶ 25-28, 850 P.2d 1069, 1077-1078, (some sections of a House Joint Resolution were severable but others were not); Tulsa Exposition & Fair Corp. v. Board of County Commissioners of Tulsa County, 1970 OK 67, 468 P.2d 501, 507, (because a statutory population classification was "an integral part of the Act” it was not severable from the rest of the Act, and the entire Act was unconstitutional).
. See, e.g., Ethics Commission v. Cullison, 1993 OK 37, ¶¶ 25-28, 850 P.2d 1069, 1077-1078, (some sections of a House Joint Resolution were severable but others were not); Elk City v. Johnson, 1975 OK 97, 537 P.2d 1215, 1217, (remainder of Okla. Const. Art. 10 § 35 remained valid after excision of invalid portion); Semke v. State ex rel. Oklahoma Motor Vehicle Commission, 1970 OK 15, 465 P.2d 441, 446, (§ 562a of the Act [47 O.S.1961, § 561-568] was severable from the portions requiring a State license for advertising and selling new or unused motor vehicles, and thus the latter portions were valid).
. One challenge to Art. 23 § 1 is based upon the National Labor Relations Act (29 U.S.C. § 151 et seq.), as amended by the Labor Management Relations Act, (61 Stat.Í40). A second challenge is based upon the Railway Labor Act (45 U.S.C. § 151 et seq.), Civil Service Reform Act (5 U.S.C. § 7101 et seq.), Postal Reorganization Act (39 U.S.C. § § 1201 etseq.), and the non-application of Art. 23 to federal enclaves. Although the certified questions involve solely the challenge based upon the Labor Management Relations Act, the plaintiffs argue that valid provisions of Article 23 may not be severed from invalid because of the Article’s inapplicability to workplaces regulated by the Railway Labor Act, Civil Service Reform Act, and Postal Reorganization Act.
. This Court presumes that legislative authority is exercised with a knowledge of this Court’s opinions. See, e.g., Bishop v. Takata Corp., 2000 OK 71, n. 14, 12 P.3d 459, 463, (discussion of legislative acquiescence to this Court’s construction of a statute). Courts are "zealous to protect and preserve” the people’s right of initiative. In re Initiative Petition No. 364, 1996 OK 129, 930 P.2d 186, 195. This presumption favors that right.
. See, e.g., Collins-Dietz-Morris Co. v. State Corporation Commission, 1931 OK 301, 7 P.2d 123, (a determination of the invalidity of an act with reference to one class of motor carriers does not require a determination of the validity of the act with reference to other classes, or affect the validity of the act as to the other classes, and the act may be sustained as to one class although unconstitutional as to the other classes).
. See also St. Paul Fire & Marine Ins. Co. v. Getty Oil Co., 1989 OK 139, 782 P.2d 915, 918, ("Whenever an act of the legislature can be so construed and applied as to avoid conflict with the constitution, and give it the force of law, such construction will be adopted by the courts.”), (Emphasis added), quoting, Williams v. Bailey, 1954 OK 19, 268 P.2d 868, 871.
. 75 O.S.2001 § 11a states:
§ 11a. Construction of statutes — Severability
In the construction of the statutes of this slate, 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 sever-able. 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.
2. For acts enacted prior to July 1, 1989, whether or not such acts were enacted with an express provision for severability, it is the intent of the Oklahoma Legislature that the act or any portion of the act or application of the act shall be severable unless:
a. the construction of the provisions or application of the act would be inconsistent with the manifest intent of the Legislature;
b. the court finds the valid provisions 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
c. the court finds the remaining valid provisions standing alone, are incomplete and are incapable of being executed in accordance with the legislative intent.
. Generally, the provisions of a Constitution are construed using the usual rules of statutory construction. Cowart v. Piper Aircraft Corp., 1983 OK 66, 665 P.2d 315, 317. We need not address whether a statutory rule of construction, § 11a, should be applied to construing Art. 23 § 1A pursuant to Cowart.
. The High Court also uses a severability analysis with federal criminal statutes. See, e.g., U.S. v. Jackson, 390 U.S. 570, 572, 88 S.Ct. 1209, 20 L.Ed.2d 138 (1968), (death penalty provision of the Federal Kidnaping Act was invalid, but sever-able from the remainder of the statute, and there was "no reason” to invalidate the law in its entirety).