with whom SAUFLEY, C.J., and LEVY, J., join, dissenting.
[¶ 34] The Court concludes that the definition of “physical or mental disability” in section 4553(7-A) of the Maine Human Rights Act (MHRA), 5 M.R.S. §§ 4551-4634 (2005), is unambiguous and does not require a plaintiff pursuing a disability discrimination complaint to prove that the disability substantially limits a major life activity, as does its federal counterpart, the Americans with Disabilities Act (ADA), 42 U.S.C.A. §§ 12101-12213 (West 2005). In my view, however, section 4553(7-A) is ambiguous, and because the Maine Human Rights Commission has reasonably interpreted section 4553(7-A) as requiring proof of a substantial limitation, we should defer to that interpretation. Accordingly, I respectfully dissent.
[¶ 35] We are called upon in this case to interpret 5 M.R.S. § 4553(7-A), which defines a “physical or mental disability” within the context of the MHRA as:
any disability, infirmity, malformation, disfigurement, congenital defect or mental condition caused by bodily injury, accident, disease, birth defect, environmental conditions or illness, and includes the physical or mental condition of a person that constitutes a substantial disability as determined by a physician or, in the case of mental disability, by a psychiatrist or psychologist, as well as any other health or sensory impairment that requires special education, vocational rehabilitation or related services.
5 M.R.S. § 4553(7-A). “When reviewing the construction of a statute, we look first to the plain meaning of the statutory language as a means of effecting the legislative intent.” Home Builders Ass’n of Me., Inc. v. Town, of Eliot, 2000 ME 82, ¶ 4, 750 A.2d 566, 569 (alterations and quotation marks omitted). If the language of the statute is ambiguous, however, “we look beyond it to the legislative history or other external indicia of legislative intent.” Irving Pulp & Paper, Ltd. v. State Tax Assessor, 2005 ME 96, ¶ 8, 879 A.2d 15, 17-18. “Ambiguous language is described as language that is reasonably susceptible of different interpretations.” Competitive Energy Servs. LLC v. Pub. Utils. Comm’n, 2003 ME 12, ¶ 15, 818 A.2d 1039, 1046 (quotation marks omitted). Further, “[t]he meaning of a statute must be construed in light of the subject matter, purpose of the statute, and the consequences of a particular interpretation.” Home *317Builders Ass’n, 2000 ME 82, ¶ 14, 750 A.2d at 571-72 (quotation marks omitted).
[¶ 36] I would conclude that the statute is ambiguous. Section 4553(7-A) states that the definition of physical disability “includes” a person’s physical condition “that constitutes a substantial disability as determined by a physician.” If that language of the statute describing a “substantial disability” is not part of the required definition of physical disability, then the “substantial disability” phrase of the statute is rendered without meaning. “In the construction of a statute, nothing should be treated as surplusage, if a reasonable interpretation supplying meaning and force is possible.” Finks v. Me. State Highway Comm’n, 328 A.2d 791, 799 (Me.1974). Moreover, it is not apparent from the language of section 4553(7-A), or any other section of the MHRA, what constitutes a “substantial disability,” and whether the test of “substantial disability” is analogous to the ADA’s test for substantial limitation of a major life activity.3
[¶ 37] Because, in my view, the definition of “physical or mental disability” in section 4553(7-A) is ambiguous, we should look beyond the plain language to determine its meaning. See Irving Pulp & Paper, 2005 ME 96, ¶ 8, 879 A.2d at 18. In doing so, we first examine the interpretation given section 4553(7-A) by the Maine Human Rights Commission.
[¶ 38] The Commission was established to administer the MHRA pursuant to 5 M.R.S. § 12004-G(15) (2005). See 5 M.R.S. § 4561. It is charged with investigating human rights violations and recommending measures to promote human rights within the State. 5 M.R.S. § 4566. To that end, the Commission is also vested with the power to promulgate rules and regulations to effectuate the provisions of the MHRA. Specifically, section 4566(7) provides that the Commission has the power “[t]o adopt, amend and rescind rules and regulations to effectuate this Act, such adoption, amendment and rescission to be made in the manner provided by chapter 375, subchapter II.”
[¶ 39] Among the rules adopted by the Commission to carry out the MHRA is Rule 3.02, which provides further definitions to accompany the MHRA. 11 C.M.R. 94 348 003-2 § 3.02 (1999). Included among these definitions is one for “physical or mental disability” which states: “An applicant or employee who has a ‘physical or mental disability’ means any person who has a physical or mental impairment which substantially limits one or more of such person’s major life activities, has a record of such an impairment, or is regarded as having such an impairment.” 11 C.M.R. 94 348 003-2 § 3.02(C)(1) (1999).
[¶ 40] We accord substantial deference to a Commission’s interpretation within its expertise of a statute it administers: “When the dispute involves an agency’s interpretation of a statute administered by it, the agency’s interpretation, although not conclusive, is entitled to great deference .... ” Maritime Energy v. Fund Ins. Review Bd., 2001 ME 45, ¶ 7, 767 A.2d 812, 814 (quotation marks omitted). If, as in this case, the statute at issue is ambiguous, we review the agency’s interpretation for “reasonableness” and must uphold that interpretation “unless the statute plainly compels a contrary result.” Competitive Energy Servs., 2003 ME 12, ¶ 15, 818 A.2d at 1046 (quotation marks omitted).
*318[¶ 41] Given the ambiguity in section 4553(7-A), the Commission’s definition of “physical or mental disability” in Rule 3.02 is reasonable, and section 4553(7-A) does not plainly compel a contrary result. Accordingly, in giving the Commission the deference due to it in the interpretation of the MHRA, I would conclude that section 4553(7-A) requires a showing of a substantial limitation on a major life activity consistent with Rule 3.02.
[¶ 42] Moreover, the reasonableness of the Commission’s interpretation of section 4553(7-A) is apparent when compared to the construction adopted by the Court. To read section 4553(7-A) as broadly as the Court does renders that section virtually unlimited in scope, and makes it applicable to even the most minor of disabilities, infirmities, malformations, disfigurements, congenital defects, mental conditions, or illnesses, etc. The Legislature is unlikely to have intended that the statute make our courts accessible on the grounds of disability discrimination when alleged ailments are so very minor or trivial. See Home Builders Ass’n, 2000 ME 82, ¶ 14, 750 A.2d at 571-72 (requiring that we interpret a statute consistently with its intended consequences).
[¶ 43] Furthermore, I do not agree that the Legislature rejected the substantial limitation language in both the Rehabilitation Act and the ADA by failing to specifically adopt it when. amending section 4553(7-A) in 1991. Rather, it is more likely that the Legislature recognized that Rule 3.02, adopted in 1985, after the effective dates of both the Rehabilitation Act and the ADA, but before 1991, contained clear substantial limitation language and that there was no need to incorporate the same language into section 4553(7-A) itself.
[¶ 44] Indeed, in my view, the Legislature has acquiesced to the Commission’s interpretation of section 4553(7-A). The law of acquiescence states:
It is a well accepted principle of statutory construction that when an administrative body has carried out a reasonable and practical interpretation of a statute and this has been called to the attention of the Legislature, the Legislature’s failure to act to change the interpretation is evidence that the Legislature has acquiesced in the interpretation.
Thompson v. Shaw’s Supermarkets, Inc., 2004 ME 63, ¶ 7, 847 A.2d 406, 409 (quoting In re Spring Valley Dev., 300 A.2d 736, 743 (Me.1973)). In this case, sincé the promulgation of Rule 3.02 defining physical disability in 1985, section 4572 of the MHRA alone has been amended at least six times, section 4553 eight times, and subsection 7-A itself has been amended once. In the twenty years since the promulgation of Rule 3.02, however, the Legislature has not clarified or altered in any way the definition of physical disability in section 4553(7-A) to indicate that Rule 3.02 is not a correct interpretation of the statute. I would conclude that the Legislature has acquiesced to the interpretation of section 4553(7-A) as promulgated by the Commission in Rule 3.02.
[¶45] Accordingly, because Rule 3.02, which requires proof of substantial limitation of a major life activity, is a reasonable and valid interpretation of section 4553(7-A), section 4553(7-A) does require that a plaintiff establish the element of substantial limitation of a major life activity in proving the existence of a physical or mental disability. I would therefore answer question # 1 in the affirmative and question # 2 in the negative.
. Our decision in Rozanksi v. A-P-A Transport, Inc., 512 A.2d 335 (Me.1986), is not dispositive of the issues now before us. Our opinion in Rozanski never considered or addressed either of the issues presented to us by the federal court, and therefore did not "necessarily reject[] the 'substantially limits’ qualification to the definition of disability,” as the Court states. Supra ¶ 21.