¶53 (dissenting) — The majority declares that a truck driver who never worked more than 40 *725hours per week in Washington is entitled to years of overtime for driving in other states: “all hours of work must be considered, whether worked within this state or not, when determining overtime due a Washington employee.” Majority at 712-13. This holding contradicts the plain language of the Washington Minimum Wage Act (MWA), chapter 49.46 RCW, that act’s statement of purpose, and an interpretive administrative rule, and runs afoul of the commerce clause. The majority’s decision also threatens to subject an important industry to the vagaries of a choice of laws analysis regarding a key business decision. Therefore, I must dissent.
J.M. Johnson, J.*725I. Relevant Facts and Provisions of Law
|54 For 10 years, Food Express, Inc., employed Larie Bostain as an interstate truck driver, driving in the states of Washington, Oregon, Idaho, and California. Majority at 706. Food Express informed Bostain from the beginning of his employment that he would not be entitled to overtime, and Food Express never paid Bostain any overtime wages. Majority at 706.
¶55 Years later, having been fired by Food Express for other reasons, Bostain now claims that he is entitled to overtime wages pursuant to RCW 49.46.130(1). Majority at 707. However, our statute, RCW 49.46.130(1), requires overtime only for workers who work over 40 hours per week within the state of Washington. Because the majority reaches a different result, applying Washington law to hours worked in Oregon, Idaho, and California, I dissent.
¶56 The statute at issue is RCW 49.46.130, titled “Minimum rate of compensation for employment in excess of forty hour work week — Exceptions.” RCW 49.46.130(1) provides that employees who work more than 40 hours per week are entitled to overtime unless a listed exception applies (see full text, infra). Neither this court nor the Court of Appeals has addressed whether RCW 49.46.130(1) *726requires overtime only where employees have worked more than 40 hours per week within the state of Washington. Two earlier cases considering the statute are not dispositive of this issue. Majority at 717; Dep’t of Labor & Indus, v. Common Carriers, Inc., 111 Wn.2d 586, 762 P.2d 348 (1988); Dep’t of Labor & Indus, v. Overnite Transp. Co., 67 Wn. App. 24, 834 P.2d 638 (1992), review denied, 120 Wn.2d 1030 (1993)).
¶57 RCW 49.46.130(1) does not explicitly address whether the “hours” relevant to the determination of overtime compensation are limited to hours worked within the state of Washington. Rather, as evidenced by the conflicting decisions below, RCW 49.46.130(1) is subject to more than one reasonable interpretation on this point. Given this ambiguity, Food Express correctly argues that other sections of the statute and relevant administrative rules may be used to interpret RCW 49.46.130(1).10 Viewed together, these provisions compel the conclusion that employees must be paid overtime under RCW 49.46.130(1) based only on hours worked within the state of Washington.
II. Rules for Statutory Interpretation
¶58 Statutory interpretation is a question of law that this court reviews de novo. Philippides v. Bernard, 151 Wn.2d 376, 383, 88 P.3d 939 (2004). “The primary goal of statutory interpretation is to ascertain and give effect to the legislature’s intent and purpose.” In re Parentage of J.M.K., 155 Wn.2d 374, 387, 119 P.3d 840 (2005). To reach this goal, this court considers first the plain language of the statute. This analysis includes examination of “the statute as a *727whole, giving effect to all that the legislature has said, and . . . using related statutes to help identify the legislative intent embodied in the provision in question.” Id.
¶59 If, after this analysis, the statute is still subject to more than one reasonable interpretation, it is ambiguous. State v. Campbell & Gwinn, LLC, 146 Wn.2d 1, 12, 43 P.3d 4 (2002). In determining legislative purpose and intent of an ambiguous statute, this court may look beyond the language of the act to its legislative history. Id. Useful legislative history materials may include bill reports. State v. Reding, 119 Wn.2d 685, 690, 835 P.2d 1019 (1992). Additionally, in construing an ambiguous statute, this court will “accord great weight to the contemporaneous construction placed upon it by officials charged with its enforcement, especially where the Legislature has silently acquiesced in that construction over a long period.” In re Sehome Park Care Ctr, Inc., 127 Wn.2d 774, 780, 903 P.2d 443 (1995).
¶60 While “[administrative agencies do not have the power to promulgate rules that would amend or change legislative enactment [,] [a]gency rules may be used to ‘fill in the gaps’ in legislation if such rules are ‘necessary to the effectuation of a general statutory scheme.’ ” Wash. Pub. Ports Ass’n v. Dep’t of Revenue, 148 Wn.2d 637, 646, 62 P.3d 462 (2003) (internal quotation marks omitted) (quoting Green River Cmty. Coll. v. Higher Educ. Pers. Bd., 95 Wn.2d 108, 112, 622 P.2d 826 (1980)). Courts give substantial weight to an agency’s interpretation of the statutes it administers. Manke Lumber Co. v. Diehl, 91 Wn. App. 793, 802, 959 P.2d 1173 (1998) (citing Weyerhaeuser Co. v. Dep’t of Ecology, 86 Wn.2d 310, 315, 545 P.2d 5 (1976)). Courts should not defer to an agency’s interpretation of a statute if that interpretation conflicts with the statutory mandate. Cockle v. Dep’t of Labor & Indus., 142 Wn.2d 801, 812, 16 P.3d 583 (2001).
III. Interpretation of the Overtime Provisions of the Washington Minimum Wage Act
¶61 RCW 49.46.130(1) contains no explicit indication that it is limited in application to employees performing *728work within the state of Washington, but also indicates no intent to apply to hours worked in other states. RCW 49.46.130(1) provides, in relevant part:
Except as otherwise provided in this section, no employer shall employ any of his employees for a work week longer than forty hours unless such employee receives compensation for his employment in excess of the hours above specified at a rate not less than one and one-half times the regular rate at which he is employed.
¶62 While RCW 49.46.130(1) is silent regarding whether an employee must work over 40 hours within the state of Washington to receive overtime pay, RCW 49.46.005 is not silent on this point. RCW 49.46.005 describes the purpose of the entire MWA as follows:
to establish minimum standards of employment within the state of Washington ... to establish a minimum wage for employees of this state to encourage employment opportunities within the state. . . . for the purpose of protecting the immediate and future health, safety and welfare of the people of this state.
(Emphasis added.)
¶63 These repeated references to the MWA’s impact on employment matters “within the state” evidence the legislature’s intent to focus the impact of the MWA on Washington employees working within the state of Washington.
¶64 In an attempt to minimize the impact of this statutory language, the majority analogizes this case to Burnside v. Simpson Paper Co., 123 Wn.2d 93, 864 P.2d 937 (1994). Majority at 711-12. In Burnside, this court held that limiting the application of the Washington Law Against Discrimination (WLAD) (chapter 49.60 RCW) in accordance with a literal interpretation of the term “inhabitants” contained in its statement of purpose would contravene the law’s fundamental purpose. Burnside, 123 Wn.2d at 99. However, Burnside may be distinguished.
¶65 As an initial matter, Burnside is distinguishable in that the defendant in that case advocated a literal inter*729pretation of a term in WLAD’s statement of purpose in order to limit the court’s subject matter jurisdiction to enforce the act. Id. at 98. No such jurisdictional challenge is mounted in the present case. More importantly, unlike in Burnside, limiting the application of the MWA in accordance with its focus on employees working within the state of Washington in no way impairs the MWA’s fundamental purpose. Interpreting the word “hours” in RCW 49.46-.130(1) to mean “hours worked in Washington State” is “plainly . . . consistent with . . . the spirit of the MWA[ ],” as evidenced by the plain language of RCW 49.46.005. Majority at 712. Furthermore, while the majority is correct that, as a general proposition, remedial statutes are to be liberally construed, this rule does not require that a statute be stretched beyond its express purpose (here stretched to apply Washington law outside the state’s borders). Majority at 712.
¶66 The legislature’s intent to focus the benefits of the MWA in general, and its overtime provision in particular, on employees working within the state of Washington is further confirmed by a long-standing administrative rule promulgated by the Department of Labor and Industries (DLI): WAC 296-128-011. This rule was adopted in 1989 with reference to RCW 49.46.130(2)(f) and this court’s decision in Common Carriers, 111 Wn.2d 586.11 Majority at 713. However, as the majority concedes, WAC 296-128-011 is not *730limited in application to workers covered by the (2)(f) exemption to RCW 49.46.130(1). Majority at 715. On its face, the rule is broadly applicable. Thus, it may be used to help resolve the ambiguity in RCW 49.46.130(1) regarding the “hours” relevant to computing overtime compensation for employees covered by the federal Motor Carrier Act (FMCA) (49 U.S.C. §§ 31501-31504).
¶67 WAC 296-128-011, titled “Special recordkeeping requirements,” provides:
(1) In addition to the records required by WAC 296-128-010, employers who employ individuals as truck or bus drivers subject to the provisions of the Federal Motor Carrier Act shall maintain records indicating the base rate of pay, the overtime rate of pay, the hours worked by each employee for each type of work, and the formulas and projected work hours used to substantiate any deviation from payment on an hourly basis pursuant to WAC 296-128-012. The records shall indicate the period of time for which the base rate of pay and the overtime rate of pay are in effect.
For the purposes of this section and WAC 296-128-012, “base rate of pay” means the amount of compensation paid per hour or per unit of work in a workweek of forty hours or less .... “Overtime rate of pay” means the amount of compensation paid for hours worked within the state of Washington in excess of forty hours per week and shall be at least one and one-halftimes the base rate of pay.
(Emphasis added.) WAC 296-128-011 confirms that to receive overtime under RCW 49.46.130(1), an employee must work more than 40 hours per week within the state of Washington.
¶68 The majority does not attempt to reconcile the language of the above rule with its decision that RCW 49.46.130(1) applies to all “Washington-based” employees who work any hours at all within the state of Washington. Rather, the majority simply disregards the rule altogether. *731First, the majority justifies its decision to ignore this rule by claiming that RCW 49.46.130(1) is not ambiguous. Majority at 716. Second, the majority reasons that the above rule is inapposite because it is “inconsistent with the statutes [it] implement[s].” Majority at 715. The majority is wrong on both counts. Accordingly, the majority also erred in not deferring to the reasoned interpretation of RCW 49.46-.130(1) by DLL
¶69 Deference is accorded an agency’s interpretation of a statute only if “(1) the particular agency is charged with the administration and enforcement of the statute, (2) the statute is ambiguous, and (3) the statute falls within the agency’s special expertise.” Majority at 716 (citing Edelman v. State ex rel. Pub. Disclosure Comm’n, 152 Wn.2d 584, 590, 99 P.3d 386 (2004); Port of Seattle v. Pollution Control Hearings Bd., 151 Wn.2d 568, 587, 90 P.3d 659 (2004); Seattle Bldg. & Constr. Trades Council v. Apprenticeship & Training Council, 129 Wn.2d 787, 799, 920 P.2d 581 (1996)) (some citations omitted). The majority does not dispute that DLI is charged with the administration and enforcement of the MWA or that the statute falls within DLI’s special expertise.12 Rather, the majority concludes that deference to DLI’s rule is unnecessary because RCW 49.46.130(1) is “not ambiguous with regard to hours worked for purposes of determining when overtime compensation is due.” Majority at 716.
f 70 As noted above, a statute is ambiguous if it is subject to more than one reasonable interpretation. Campbell & Gwinn, 146 Wn.2d at 12. Here, RCW 49.46.130(1) has in fact been subject to more than one reasonable interpretation regarding overtime hours as evidenced by the conflicting decisions of the trial court and Court of Appeals. *732Bostain v. Food Express, Inc., 127 Wn. App. 499, 501, 504, 111 P.3d 906 (2005). Moreover, Bostain himself has apparently switched views as to the meaning of the term, given that he made no claim for overtime during the 10 years he was employed by Food Express. In sum, there can be no real dispute that reasonable minds have differed, and continue to differ, as to the meaning of RCW 49.46.130(l)’s reference to “hours” for purposes of overtime compensation. Id. at 511 (Morgan, J., concurring). Accordingly, the three part test for deference to an agency’s interpretation of a statute is satisfied here and this court should be guided in deciding the present case by WAC 296-128-011. Cf. Inniss v. Tandy Corp., 141 Wn.2d 517, 529, 7 P.3d 807 (2000) (relying, in part, on DLI’s interpretation of term “regular rate” as used in RCW 49.46.130(1)).
¶71 In addition to asserting that RCW 49.46.130(1) is not ambiguous, the majority argues that it may ignore WAC 296-128-011 because the rule is “inconsistent with the statutes [it] implement[s].” Majority at 715. This alleged inconsistency arises from the fact that DLI’s rule explicitly defines the term “hours” for overtime purposes as limited to hours worked within the state of Washington, while RCW 49.46.130(1) does not contain a similar limitation. Id. Yet, further refining the meaning of statutory terms used, but not defined, in the MWA is precisely the function which DLI’s rules are meant to perform. Edelman, 152 Wn.2d at 590 (“An agency charged with the administration and enforcement of a statute may interpret ambiguities within the statutory language through the rule-making process.”). There is no irreconcilable conflict between the plain language of RCW 49.46.130(1) and that of WAC 296-128-011. Rather, the latter provision simply serves to interpret the former, in accordance with DLI’s authority and expertise. Accordingly, the majority errs in refusing to look to WAC 296-128-011 for guidance in reaching its decision in this case. See In re Sehome Park Care Ctr., 127 Wn.2d at 780 (“In interpreting a statute, we accord great weight to the contemporaneous construction placed upon it by officials charged with its enforcement. . . .”).
*733¶72 Furthermore, it should be noted that the legislature has not changed the regulatory scheme for interstate truck drivers since WAC 296-128-011 was adopted in 1989. In other words, for the past 15 years, the legislature has acquiesced in the DLI’s approach to defining “hours” for purposes of awarding overtime compensation under RCW 49.46.130(1). Contrary to the suggestions of the majority, majority at 716, this legislative acquiescence is relevant to this court’s decision. See In re Sehome Park Care Ctr., 127 Wn.2d at 780 (stating that this court will give “great weight” to agency construction, “especially where the Legislature has silently acquiesced in that construction over a long period”); see also Cockle, 142 Wn.2d at 834 (Guy, J., concurring in dissent) (noting that the legislature had “had ample opportunity to clarify the statute [RCW 51.08.178] if it felt that the Department [of Labor and Industries] was misinterpreting it”).
¶73 In addition, this court must always seek to construe statutes in a manner that avoids constitutional problems. The majority’s interpretation of RCW 49.46.130(1) likely runs afoul of the commerce clause, U.S. Const, art I, § 8, cl. 3. See State v. Heckel, 143 Wn.2d 824, 837, 24 P.3d 404, cert. denied, 534 U.S. 997 (2001). Implicit in the commerce clause is “the principle that the states impermissibly intrude on . . . federal power when they enact laws that unduly burden interstate commerce.” Id. at 832. Under the majority’s interpretation, RCW 49.46.130(1) violates the commerce clause because the burden it imposes on interstate commerce is clearly excessive relative to the MWA’s express public purpose. See id.; see also Pike v. Bruce Church, Inc., 397 U.S. 137, 142, 90 S. Ct. 844, 25 L. Ed. 2d 174 (1970).
¶[74 Interpreting RCW 49.46.130(1) to apply to all hours worked by an employee when those hours are worked outside of Washington means that the MWA will inevitably burden the extraterritorial activities of interstate truck drivers and their employers. For example, a truck driver could work for 15 hours in Washington, 15 hours in Oregon, *734and 15 hours in California in a single week. Application of RCW 49.46.130(1) in the manner advocated by the majority would require his employer to track and pay overtime related to the driver’s hours worked in Oregon and California, as well as Washington. Should this driver’s employer wish to avoid paying overtime under the MWA, he might move his operation to another state or at least limit the driver’s “on duty” hours while the driver engaged in work outside of Washington. Additionally, this employer would be faced with the unenviable task of researching and resolving any conflicts between the overtime laws of Washington, Oregon, and California.13 In sum, under the majority’s interpretation, RCW 49.46.130(1) will unquestionably burden the interstate activities of the trucking industry.
¶75 A statute will fail under the Pike balancing test and thus violate the commerce clause if the burden it imposes on interstate commerce is “clearly excessive in relation to the putative local benefits.” 397 U.S. at 142. As noted above, the public purpose of the MWA is focused on promoting employment and compensating employees within the state of Washington. Thus, the burden on interstate commerce that will result from the majority’s interpretation of RCW 49.46.130(1) is largely unrelated to promotion of the public interests underlying the MWA. Because giving extraterritorial effect to RCW 49.46.130(1) will not actually further the legitimate public interests behind the MWA, the burden the majority imposes is excessive.14 See Edgar v. MITE Corp., 457 U.S. 624, 642, 102 S. Ct. 2629, 73 L. Ed. 2d 269 (1982).
¶76 Finally, while discarding the bright-line rule regarding overtime compensation for interstate truck drivers that *735has existed for the past 15 years, the majority offers the trucking industry, its employees, and its customers nothing more than a vague and unpredictable legal future regarding overtime compensation. Specifically, the majority suggests that, following its decision in this case, “[w]hether overtime under RCW 49.46.130(1) must be paid for an employee as a Washington-based employee will depend on factors that courts routinely use for deciding choice of laws issues.” Majority at 713 n.5. The average employer (or trucker) is hardly equipped to perform a choice of laws analysis for every employee potentially considered to be “Washington-based.” See Burnside, 123 Wn.2d at 100 (discussing Washington’s approach to choice of law questions). The rules regarding whether an employee must be paid overtime compensation under the MWA should facilitate the decision-making process on the ground, not hinder it. See Williams v. W.M.A. Transit Co., 153 U.S. App. D.C. 183, 472 F.2d 1258, 1265 (1972) (explaining need for overtime compensation rule “which can be applied with reasonable simplicity by area businessmen”). The majority’s “solution” for future overtime compensation decisions will result only in more confusion and litigation regarding whether or not a given interstate trucker is entitled to overtime pay. This was not the legislature’s intent in enacting RCW 49-.46.130(1). See Berrocal v. Fernandez, 155 Wn.2d 585, 595, 121 P.3d 82 (2005) (noting that “the legislature likely did not intend ... an impractical system” under the overtime provisions of the MWA).
IV. Conclusion
¶77 RCW 49.46.130(1) requires overtime compensation only for employees who work over 40 hours per week within the state of Washington. Because Bostain did not work over 40 hours per week within the state of Washington, he is *736not entitled to overtime compensation.15 Accordingly, I dissent.16
Sanders, Bridge, and Owens, JJ., concur with J.M. Johnson, J.
Reconsideration denied June 20, 2007.
While I reach the same conclusion in this dissent as was reached by the Court of Appeals, my rationale is different in that I conclude RCW 49.46.130(1) is ambiguous regarding the central issue. See Bostain v. Food Express, Inc., 127 Wn. App. 499, 506, 111 P.3d 906 (2005); but see Bostain, 127 Wn. App. at 511 (Morgan, J., concurring). This ambiguity makes it appropriate to look to related administrative rules as well as the statute’s legislative history for guidance in interpreting RCW 49.46.130(1). City of Pasco v. Pub. Employment Relations Comm’n, 119 Wn.2d 504, 509, 833 P.2d 381 (1992); State v. Campbell & Gwinn, LLC, 146 Wn.2d 1, 12, 43 P.3d 4 (2002).
The federal Fair Labor Standards Act (FLSA), 29 U.S.C. § 213(b)(1), exempts from federal overtime compensation interstate truck drivers under the federal Motor Carrier Act (FMCA) (49 U.S.C. §§ 31501-31504). In Common Carriers, this court held that the FMCA did not preempt the MWA’s overtime wage provisions. 111 Wn.2d at 590. The effect of this holding was to subject interstate truck drivers in Washington to an overtime scheme, namely, RCW 49.46.130(1). To reverse this result, the legislature adopted the exemption in (2)(f):
(2) This section [RCW 49.46.130(1)] does not apply to:
(f) An individual employed as a truck or bus driver who is subject to the provisions of the Federal Motor Carrier Act [49 U.S.C. § 31501 et seq.], if the compensation system under which the truck or bus driver is paid includes overtime pay, reasonably equivalent to that required by this subsection, for working longer than forty hours per week ....
Laws op 1989, ch. 104, § 1; Final Legislative Report, 51st Leg., at 267 (Wash. 1989). While Bostain is a truck driver subject to the FMCA, he does not come within the *730(2)(f) exemption because Food Express did not provide him with overtime compensation or its reasonable equivalent. Since Bostain does not come within the (2)(f) exemption, RCW 49.46.130(1) applies.
DLI has the authority to supervise, administer, and enforce all laws pertaining to employment, including wage and hour laws. RCW 43.22.270. Moreover, the determination of the meaning of particular terms within the MWA’s overtime compensation provisions is within DLI’s specialized expertise. Cf. Schneider v. Snyder’s Foods, Inc., 116 Wn. App. 706, 717, 66 P.3d 640 (concluding that “determination of whether a compensation scheme constitutes the reasonable equivalent of statutory overtime is within the Department’s specialized expertise”), review denied, 150 Wn.2d 1012 (2003).
For example, unlike the MWA, Oregon Administrative Rule 839-20-0125(3) tracks the FLSA exemption for employees subject to the FMCA and, accordingly, does not provide overtime for interstate truck drivers.
While the Court of Appeals held in Overnite Transp. Co., 67 Wn. App. at 32, that application of the MWA’s overtime provisions to interstate motor carriers did not unduly burden interstate commerce, that case was explicitly limited in its analysis to employees working over 40 hours per week within the state of Washington.
An audit of Bostain’s final year of work for Pood Express showed that Bostain averaged a total of 48 hours of driving/loading but that he never worked more than 40 hours per week within the state of Washington. Majority at 707.
My conclusion regarding the meaning of “hours” for purposes of ROW 49.46.130(1) and, thus, that Food Express should prevail before this court necessitates that I also dissent from the majority’s determination regarding costs and fees. I would affirm the Court of Appeals decision to grant Food Express attorney fees. Bostain, 127 Wn. App. at 510.