dissenting. Because I conclude that, under the doctrine of primary jurisdiction, the superior court erred in enjoining the ongoing enforcement proceedings before the banking department, I would reverse.
Perhaps the best elucidation of the doctrine of primary jurisdiction is that found in a prominent administrative law treatise:
The precise function of the doctrine of primary jurisdiction is to guide a court in determining whether the court should refrain from exercising its jurisdiction until after an administrative agency has determined some question or some aspect of some question arising in the proceeding before the court. The doctrine of primary jurisdiction does not necessarily allocate power between courts and agencies, for it governs only the question whether court or agency will initially decide a particular issue, not the question of whether court or agency will finally decide the issue.
3 K. Davis, Administrative Law Treatise § 19.01, at 3 (1958), quoted in Sears, Roebuck & Co. v. Carpenters, 436 U.S. 180, 199 n.29 (1978); see also Pharmaceutical Research and Mfrs. of American Walsh, 538 U.S. 644, 673 (2003) (Breyer, J., concurring in part and concurring in the judgment) (“[Primary jurisdiction] seeks to produce better informed and uniform legal rulings by allowing courts to take advantage of an agency’s specialized knowledge, expertise, and central position within a regulatory regime.”); Konefal v. Hollis/Brookline Coop. School Dist., 143 N.H. 256, 258 (1998) (“Primary jurisdiction in an agency requires judicial abstention until the final administrative disposition of an issue, at which point the agency action may be subject to judicial review.” (quotations omitted)). Because primary jurisdiction is a prudential doctrine, rather than one based on the absence *380of judicial power,1 there is no “fixed formula” for determining when the doctrine applies. United States v. Western Pac. R. Co., 352 U.S. 59, 64 (1956). However, the following factors are often cited as relevant considerations in making this determination: (1) the extent to which the agency’s specialized expertise makes it a preferable forum for resolving the issue in dispute; (2) the need for uniform resolution of the issue; and (3) the potential that judicial resolution of the issue will have an adverse impact on the agency’s performance of its regulatory responsibilities. See II K. DAVIS & R. Pierce, Jr., Administrative Law Treatise § 14, at 272 (3d ed. 1994); see also Walsh, 538 U.S. at 673 (Breyer, J., concurring in part and concurring in the judgment) (“[The question], in a word, [is] whether preliminary reference of issues to the agency will promote that proper working relationship between court and agency that the primary jurisdiction doctrine seeks to facilitate.”); cf. Konefal, 143 N.H. at 258 (“The rule requiring administrative remedies to be exhausted prior to appealing to the courts is based on the reasonable policies of encouraging the exercise of administrative expertise, preserving agency autonomy and promoting judicial efficiency.” (quotations omitted)).
While acknowledging the doctrine of primary jurisdiction, the majority holds that the trial court did not unsustainably exercise its discretion in declining to apply the doctrine because the issue addressed by the trial court concerned the banking department’s subject matter jurisdiction and was purely a question of law rather than of administrative discretion. I believe the majority takes too narrow a view of the circumstances under which deference is owed to an administrative agency, and that the cases it relies on to support its position are distinguishable in important respects from this case. Accordingly, I would find that the trial court’s decision to enjoin the ongoing banking department proceedings did constitute an unsustainable exercise of discretion.
None of the cases relied on by the majority involved an effort to enjoin an ongoing administrative enforcement proceeding, i.e., a proceeding examining whether a licensee had violated a regulatory regime, a circumstance that presents a particularly compelling reason for a court to stay its hand. See Interfaith Community Organization v. PPG, 702 F. Supp. 2d 295, 310 (D.N.J. 2010); accord Dept. of Public Works v. L.G. Indus., 758 *381A.2d 950, 957 (D.C. 2000) (reversing grant of injunction against agency enforcement proceeding, and admonishing that “the trial court must be especially careful before resorting to that remedy where ... the requested relief would enjoin agency action pending the outcome of administrative review. In part the reason for this restraint is the very one that underlies the primary jurisdiction doctrine, which is that the court is acting — and risks disruption — in a field that is normally confided to the agency’s expertise” (quotations, brackets, and citation omitted)); Bar Harbor Banking & Trust Co. v. Alexander, 411 A.2d 74, 78 (Me. 1980) (lifting temporary restraining order that prevented Bureau of Consumer Protection from holding hearing to determine whether bank had violated statute regulating permissible finance charges, explaining that “[w]here the administration of a particular statutory scheme has been entrusted to an agency, the Court will postpone consideration of an action until the agency has made a designated determination if such postponement will protect the integrity of the statutory scheme” (quotation omitted)); Luskin’s Inc. v. Consumer Protection, 657 A.2d 788, 793 (Md. 1995) (holding that primary jurisdiction doctrine required dismissal of declaratory judgment action filed by merchant subject to agency proceedings for misleading consumer advertising); Zar v. S.D. Bd. of Examiners of Psychologists, 376 N.W.2d 54, 55 (S.D. 1985) (reversing writ of prohibition preventing disciplinary proceedings against licensee; trial court had reasoned that it should make initial decision as to whether Board lacked jurisdiction to discipline licensee because of alleged invalidity of administrative rules; supreme court disagreed, citing Myers v. Bethlehem Corp., 303 U.S. 41 (1938), for proposition that “[u]nder the doctrine of separation of powers, an administrative agency, a branch of the executive department, is empowered to determine its own jurisdiction” in the first instance); cf. Smith v. N.H. Bd. of Psychologists, 138 N.H. 548, 554 (1994) (reversing trial court’s entry of injunction that prevented Board of Examiners of Psychologists from conducting disciplinary proceedings involving licensees).
Unlike the instant case, Wisniewski v. Gemmill, 123 N.H. 701 (1983), on which the majority primarily relies, did not involve an action in which the plaintiff sought an injunction against the regulatory agency itself; indeed, the agency (the former water resources board) was not even a party to that case. Instead, the lawsuit was a common law action for damages between private parties in which the defendant sought dismissal based on the argument that, because the suit concerned the alteration of the course of a public water body, the board had exclusive jurisdiction. Id. at 705. Moreover, unlike this case, where the banking department was actively pursuing administrative proceedings against petitioner Frost and had extended him the opportunity for a hearing at the time he sought judicial *382relief, in Wisniewski, the agency proceedings had lain dormant for nine months before suit was filed. See id. at 704; cf. Coit Independence Joint Venture v. FSLIC, 489 U.S. 561, 586-87 (1989) (expressing concern that requiring exhaustion of administrative remedies would relegate parties to a dispute resolution process the Court described as a “black hole”). Furthermore, none of the parties before the court in Wisniewski was a licensee of the water resources board, nor did the board have the authority to award the type of relief, i.e., monetary damages, that the plaintiff was seeking. See Wisniewski, 123 N.H. at 707. Here, by contrast, Frost was a licensee of the banking department, and, as the majority recognizes, the department therefore unquestionably had “regulatory authority” over him. Thus, even accepting the majority’s construction of “engage in the business” as used in RSA 397-A:2 (2006 & Supp. 2011), the department, at worst, had a mistaken view of the scope of its regulatory authority. But no one disputes that this was an issue Frost could have challenged, and the department could have decided, at an administrative hearing, which would have to have been conducted pursuant to the provisions of the Administrative Procedures Act governing adjudicative proceedings. See RSA 397-A:17, III (2006); RSA 541-A:30, III (2007). Collectively, the foregoing considerations demonstrate that this case presents a far more compelling argument for invoking primary jurisdiction than did Wisniewski.
The other cases cited by the majority, Pheasant Lane Realty Trust v. City of Nashua, 143 N.H. 140 (1998), Bedford Residents Group v. Town of Bedford, 130 N.H. 632 (1988), and Metzger v. Brentwood, 115 N.H. 287 (1975), also are distinguishable. Not only did none of those cases involve agency enforcement proceedings, but the land use and/or property tax statutes at issue in those cases were also not nearly as complex — or the legal position of the governmental body as arguable — as that presented here. It is a well-recognized principle of administrative law that where the legislature has described an agency’s powers in broad and ambiguous language, the agency generally is given the first opportunity to rule upon the extent of its jurisdiction. Although we have not gone so far as to adopt the federal rule, which requires courts to defer to an agency’s reasonable construction of an agency-administered statute, see Chevron U.S.A., Inc. v. Natural Res. Def. Council, 467 U.S. 837, 843-45, 866 (1984), we have long taken the view that substantial deference is due to the interpretation placed on a statute of doubtful meaning by the agency charged with its implementation. See Grand China v. United Nat’l Ins. Co., 156 N.H. 429, 434 (2007); cf. Win-Tasch Corp. v. Town of Merrimack, 120 N.H. 6, 9-10 (1980). The doctrine of primary jurisdiction complements our substantial deference policy by ensuring that an agency is given the first opportunity *383to construe an ambiguous statute. See Verizon New England v. Maine Public Utilities, 509 F.3d 1, 11-12 (1st Cir. 2007). As Professor Pierce explains:
The primary jurisdiction doctrine often compels a court to refer an issue to an agency... when the issue ultimately is determined not to be within the agency’s statutory jurisdiction. The resulting situation — an agency’s primary jurisdiction is often broader than its statutory jurisdiction — seems strange at first glance. It makes eminently good sense, however, upon examination of the nature and frequent difficulty of determining the scope of the agency’s statutory jurisdiction.
IIR. Pierce, Jr., Administrative Law Treatise § 14.2, at 1185 (5th ed. 2010). Put another way, the primary jurisdiction doctrine comes into play when conduct that is the subject of court litigation “is ... at least arguably protected or prohibited by a . . . regulatory statute” and when agency resolution of an issue is likely to be of “material aid” to judicial resolution of the dispute. Ricci v. Chicago Mercantile Exchange, 409 U.S. 289, 299-300, 302 (1973); see Clark v. Time Warner Cable, 523 F.3d 1110, 1115-16 (9th Cir. 2008) (referring matter to agency where issue was novel, agency regarded resolution of issue as important to policies it was required to implement, and agency had issue under active consideration); cf. Leedom v. Kyne, 358 U.S. 184, 188-89 (1958) (declining to require exhaustion of administrative remedies when agency action is plainly ultra vires).
At the times pertinent to this case, RSA chapter 397-A established a comprehensive regulatory scheme for “persons that engage in the business of making or brokering” certain mortgage loans. RSA 397-A:2,1 (2006). If the “engage in the business” language found in RSA 397-A:2, I, were the only pertinent section regarding the scope of the statute, I would agree with the majority that the statute does not reach the two isolated mortgage loan transactions conducted by Frost Family and Chretien. However, this is not the case. Instead, RSA 397-A:3,1 (2006 & Supp. 2011) provides: “Any person not exempt under RSA 397-A:J¡, that, in its own name or on behalf of other persons, engages in the business of making or brokering mortgage loans secured by real property located in this state shall be required to obtain a license from the department.” (Emphasis added.) And, when these transactions occurred, RSA 397-A:4 (2006) provided, in relevant part, that RSA chapter 397-A was inapplicable to:
II. Any natural person making not more than 4 first mortgage loans within any calendar year with the person’s own funds and for the person’s own investment without an intent to resell such mortgage loans.
*384III. Any natural person who, as seller, receives one or more first or second mortgages or deeds of trust on real estate as security for a purchase money obligation.
(Emphases added.)
Because neither Frost Family nor Chretien is a “natural person,” neither was covered by these exemptions.2 More importantly, the existence of these statutory exemptions results in an ambiguity as to the intended meaning of the “engage in the business” term found in RSA 397-A:2, I, and :3. The effect of the first exemption is to create a safe harbor for natural persons who make fewer than five first mortgage loans within a calendar year. The effect of the second is to exclude any natural person who provides a first or second mortgage as part of seller-financing in connection with even one property he or she sells to another. Contrary to the majority’s suggestion, it is not proper to simply ignore these exemptions in construing the scope of the banking department’s authority under RSA chapter 397-A. Indeed, failing to consider the exemptions in determining what is meant by the term “engage in the business” of making or brokering loans is inconsistent with a first principle of statutory interpretation — that statutory provisions are not to be considered in isolation but in the context of the entire statutory scheme. State v. Jennings, 159 N.H. 1, 3 (2009). By failing to consider the overall statutory scheme, the majority offers no answer to what is the seminal question that must be addressed in order to properly construe the statute: If the legislature intended “engage in the business” to cover only non-natural persons who regularly or habitually make or broker mortgage loans, why would it have found it necessary to specifically exclude them in the above exemptions?3 See State v. Pierce, 152 N.H. 790, 791 (2005) (“All words of a statute are to be given effect, and the legislature is presumed not to use words that are superfluous or redundant.”). Reading the statute as a whole, one plausible construction is that the legislature intended non-natural persons, such as Frost Family and Chretien, to be *385deemed “engaged in the business” of making or brokering mortgages even if they engage in only a single transaction. And, of course, if the statute is construed so as to require Frost Family and Chretien to have been licensed, then there is a basis for the banking department’s investigation into whether Frost (1) made misrepresentations in his application for licensure as a loan originator, (2) serviced loans for non-licensed mortgage bankers, and (3) simultaneously represented more than one mortgage banker. See RSA 397-A:l, XVII, :3, III, :17 (2006 & Supp. 2011).4
To be clear, it is not my purpose to attempt a definitive construction of RSA chapter 397-A. Given the statute’s ambiguity, it may be that ultimately I too would come to the conclusion that the most sensible construction of RSA 397-A:2 and :3 would exclude Frost Family and Chretien from being “engaged in the business” of making or brokering mortgage loans.5 To me, the critical point is that any such construction of the statute by either the trial court or this court is premature at this time. Rather, in my view, where, as here, the banking department had not obviously overstepped the *386bounds of its authority, respect for the proper functioning of an agency of a coordinate branch of government that has been given primary jurisdiction to regulate in the field réquired the trial court to refrain from interfering with the ongoing administrative proceedings.
In closing, I also must note my concern that today’s decision may pave the way for future licensees to attempt to circumvent agency enforcement proceedings any time imaginative counsel is able to fashion a plausible argument that the agency has misinterpreted its regulatory authority. Needless to say, such a development would not be consonant with sound public policy.
For the reasons stated above, I respectfully dissent.
DUGGAN, J., retired, specially assigned under RSA 490:3, joins in the dissent.Although not grounded in an absence of judicial power, the primary jurisdiction doctrine does implicate separation of powers concerns because it relates to the relationship between the branches of government. See, e.g., Travelers Ins. Co. v. Detroit Edison Co., 631 N.W.2d 733, 741 (Mich. 2001) (noting that one of the justifications for the primary jurisdiction doctrine “relates to respect for the separation of powers and the statutory purpose underlying the creation of the administrative agency, the powers granted to it by the legislature, and the powers withheld!; tjhis justification includes the principle that courts are not to make adverse decisions that threaten the regulatory authority and integrity of the agency”).
Nor do petitioners argue that any other provisions of RSA 397-A:4 in effect at the relevant times exempt Frost Family or Chretien from the reach of RSA chapter 397-A.
Insofar as the RSA 397-A:4, II exemption is designed to establish a safe harbor for a course of conduct that might otherwise constitute “engaging in the business,” it might be contended that the exclusion of non-natural persons from this exemption was merely intended to disqualify entities (non-natural persons) from the safe harbor, not to signify that entities did not have to make or broker mortgages with some level of regularity in order to be engaged in the business. The same argument cannot be made as to the RSA 397-A:4, III exemption. The fact that, with respect to natural persons, the legislature found it necessary to include a specific exemption for a person who makes even one seller-financing mortgage suggests that without the exemption such person could be considered engaged in the business of making mortgages; and, of course, the exemption does not apply to non-natural persons even if they make only one seller-financing mortgage.
Both the petitioners and the trial court seemed to recognize that the meaning of the statute was less than completely clear. This is demonstrated by the fact that the petitioners found it necessary to provide the trial court with an expert report from a banking law attorney opining on his interpretation of the scope of activity falling within the reach of the statute. The trial court considered this report and found it “valuable and helpful.” It also is demonstrated by the trial court’s denial of the petitioners’ request for attorney’s fees. Rejecting the petitioners’ claim that the defendants acted in bad faith, the court found, “[the banking department] took a legal position which involved complex statutes and their application to a highly regulated industry.”
I cannot agree with the majority that the legislative history of the 2011 amendment to RSA 397-A:4 supports its construction of the 2005 version of the statute — the version that is controlling with respect to the conduct at issue. On this point, I note initially that the very fact that the majority deems it necessary to reference legislative history confirms my view that, prior to the 2011 amendment, the statute was ambiguous with respect to whether Frost Family and Chretien were engaged in the business of making or brokering mortgages. See Appeal of Cote, 144 N.H. 126, 129 (1999) (“While legislative history may be helpful in the interpretation of an ambiguous statute, it will not be consulted when the statutory language is plain.” (quotation omitted)). More importantly, while the actions of Frost Family and Chretien would appear to have been exempt if they had occurred after the 2011 amendment to RSA 397-A:4 had taken effect, that amendment clearly did more than clarify pre-existing law. On the contrary, as its legislative history makes clear, the amendment was intended to change existing law to expand the circumstances in which seller-financing of real estate transactions would be allowed without the need for the seller to be licensed. See Hearing ON SB 28 before Senate Commerce Comm. (Jan. 25, 2011) (testimony of Sen. Boutin) (“This de minimis exemption would allow a number of the transactions which cannot be completed now while ensuring that the exemption will not undermine the current law.” (emphasis added)); N.H.H.R. JOUR. ___ (May 25, 2011) (remarks of Rep. Manuse) (“Current law requires any person to get a mortgage loan originators license from the New Hampshire banking department, even in harmless circumstances when licensing private citizens who intend to make up to three loans is not practical.” (emphasis added)). The 2011 amendment is the first time the legislature clearly created a safe harbor exemption that covers non-natural persons such as Frost Family and Chretien.