OPINION

Our jurisdiction in this appeal has been challenged by.motion of the appellee, the Waller County Sub-Regional Planning Commission, which asserts that the trial-level rulings being brought before us are interlocutory and have not been made ap-pealable by statute. We requested and received a response from the appellant, James Bass, in his official capacity as Executive Director of the Texas Department of Transportation. While acknowledging there is no final judgment, the Executive Director argues that we possess jurisdiction under Section 51.014(a)(8) of the Civil Practice and Remedies Code, the statute that authorizes the appeal of an interlocutory order from a district court that “grants or denies a plea to the jurisdiction by a governmental unit.”1 We conclude that we lack jurisdiction for reasons that *910may represent some new wrinkles in Texas jurisprudence addressing appeals of interlocutory orders under color of Section 51.014(a)(8).

BACKGROUND

The underlying litigation arises along one of the larger faultlines of policy and priorities found in modern-day Texas—the recurrent tensions between advocates of large-scale transportation projects to connect our State’s urban centers versus those who perceive detriment to the less populous regions lying between. Currently in development—with integral TxDOT involvement—is a high-speed railway project that would connect Dallas and Houston. In the project’s anticipated path lies Waller County, the region served by the Planning Commission,2 and that body has demanded a seat at the planning table by virtue of Section 391.009(c) of the Local Government Code, which states that “state agencies,” “[i]n carrying out their planning and program development responsibilities, ... shall, to the greatest extent feasible, coordinate planning with” regional planning commissions “to ensure effective and orderly implementation of state programs at the regional level.”3 But according to the Planning Commission, TxDOT has refused to “coordinate” with it in this manner and instead proceeded “at full steam” with planning and studies focused on a single “pre-selected route” through Waller County that is favored by the project’s private developer, to the exclusion of other alternative routes more favorable to local concerns. In fact, the Planning Commission further complains, TxDOT has advised that it will not so “coordinate” until after the completion of a draft environmental-impact study based on the “pre-selected route,” a process that the Planning Commission perceives will deprive it—and the local interests it represents—of any meaningful input in the project’s ultimate routing and placement.

Based on these and other allegations, and adhering to the conceptual and procedural framework for claims challenging governmental conduct alleged to be ultra vires of legal authority,4 the Planning Commission has sued the Executive Director, in his official capacity, seeking declarations establishing the existence of the aforementioned claimed duty of TxDOT under Section 391.009(c) to “coordinate” with the Planning Commission “to the greatest extent feasible” and that this duty has been violated.5 The Planning Commission has further prayed for mandamus and mandatory injunctive relief against the Executive Director to compel compliance with this duty prospectively. In response, the Executive Director has answered, interposed a plea to the jurisdiction as to the Planning Commission’s claims for declaratory and injunctive relief, and also filed a Rule 91a motion to dismiss the Planning Commission’s claims for mandamus relief.6 *911The plea to the jurisdiction principally asserts sovereign immunity and, in support of both his plea and Rule 91a motion, the Executive Director has disputed that Section 391.009(c) imposes any duty on TxDOT that would be considered ministerial or non-discretionary or could otherwise have been violated.7

The Planning Commission also filed a motion for partial summary judgment seeking the declaratory relief for which it had pleaded. The Executive Director filed a response in which he reurged his jurisdictional challenges regarding the declaratory claims as grounds for denying the motion. He added, as further grounds for denying the motion, that fact issues precluded summary judgment and that Section 391.009(c) had no application to the high-speed-rail project in the first place.8

The district court heard oral argument on the Planning Commission’s motion for partial summary judgment, the Executive Director’s plea to the jurisdiction, and the Executive Director’s Rule 91a motion during a hearing held on January 5, 2017. Before the hearing’s conclusion, the district court signed an “Order Granting Plaintiffs Motion for Partial Summary Judgment” granting the Planning Commission’s motion and awarding it substantially the same declaratory relief it had requested in its pleadings.9 Subsequent to the hearing, the district court signed a second order, also dated January 5, 2017, titled “Order on Defendant’s Plea to Jurisdiction and Rule 91a Motion to Dismiss.” In it, the court denied the Executive Director’s Rule 91a motion but concluded that “existing fact questions regarding the jurisdictional issue should be resolved by the fact finder at trial.” Accordingly, the order states that the district court “declines to rule on the Plea to the Jurisdiction at this time,” and “that the determination of Defendant’s Plea to the Jurisdiction is reserved for trial.” The relative timing of the two orders, which the Executive Director acknowledges, will eventually become significant to our analysis.10

*912On January 13, 2017—within the twenty-day deadline that would govern a permissible interlocutory appeal11—the Executive Director filed a notice of appeal purporting to challenge both orders. The Planning Commission’s motion challenging our jurisdiction over that appeal followed.

ANALYSIS

In ascertaining whether we have jurisdiction here, our starting point is that appeals generally may only be taken from final judgments or orders and that appeals of interlocutory orders are authorized only if and to the extent explicitly permitted by statute.12 A corollary principle is that we “strictly construe” statutes that would authorize appeals of interlocutory orders, as they represent a “ ‘narrow exception to the general rule that only final judgments are appealable.’ ”13

As the Planning Commission emphasizes in its dismissal motion, the Legislature has thus far not seen fit to authorize—at least categorically—appeals of interlocutory orders granting partial summary judgment (the subject of the district court’s first order), or those denying Rule 91a motions (as contained in its second order).14 Nor, as the Planning Commission adds, has the Legislature authorized the appeal of a trial court’s interlocutory decision to reserve determination of a jurisdictional challenge, as the district court explicitly did with the Executive Director’s plea to the jurisdiction. It is well established that a trial court faced with a jurisdictional challenge is not necessarily obligated to decide the issue immediately, but possesses some discretion to defer that determination pending further record development, conceivably even until trial on the merits.15 There is no complaint before us that the district court abused this discretion here,16 and the court’s decision to defer its jurisdictional ruling would not *913be reviewable by interlocutory. appeal in any event. While Section 51.014(a)(8) of the Civil Practice and Remedies Code provides the Executive Director a means of appealing an interlocutory order that “grants or denies” his jurisdictional challenges,17 an order deferring or otherwise declining to rule on a jurisdictional challenge falls outside that authorization. This Court so held in its recent CCNG Development ease,18 and our sister courts are in accord.19

The Executive Director does not appear to contest any of these propositions. He insists, rather, that we possess jurisdiction under Section "51.014(a)(8) by virtue of an implicit denial of his jurisdictional challenges made by the district court when granting the Planning Commission’s motion for partial summary judgment. His reasoning rests upon two principles recognized in case law- applying Section 51.014(a)(8). First, the Texas Supreme Court has concluded- that/ Section 51.014(a)(8)’s authorization of an ..appeal of an order that “grants or denies a plea to the jurisdiction” refers not to that specific type or form of filing, but to any challenge to subject-matter jurisdiction irrespective of the procedural vehicle used.20 It follows, as the Executive Director urges, that his reurging of his jurisdictional challenges in his summary-judgment response could potentially serve as a predicate for an appeal under Section 51.014(a)(8) to the same extent as his plea to the jurisdiction would.21

The second principle, also recognized by the Texas Supreme Court, is that *914a denial of a jurisdictional challenge reviewable under Section 51.014(a)(8) need not necessarily be made explicitly by the trial court, but is among the trial-court rulings that may be implied from context, as contemplated by appellate rule 33.1(a)(2)(A).22 The leading case in that regard is Thomas v. Long, which involved facts somewhat similar to the present case—a plaintiff (Long) sued the Harris County Sheriff (Thomas), asserting claims for declaratory and mandamus relief, moved for partial summary judgment on both claims, and Thomas responded with a cross-motion for summary judgment arguing, in part, that the trial court lacked subject-matter jurisdiction over either claim.23 The trial court granted Long’s motion as to the declaratory claim, with a corresponding partial denial of Thomas’s cross-motion, and rendered a partial judgment granting Long the declaratory relief she had sought.24 Thomas then brought an appeal under color of Section 51.014(a)(8) in which he sought to challenge the trial court’s denial of his motion for summary judgment disputing the trial court’s jurisdiction.25 The court of appeals dismissed the appeal, reasoning that there was no order explicitly granting or denying a plea to the jurisdiction.26 The Texas Supreme Court reversed, reasoning that Thomas had raised his jurisdictional challenge through his summary-judgment motion and that this challenge had been denied implicitly through the trial court’s awarding of declaratory relief.27 The high court reasoned:

To be entitled to an interlocutory appeal, section 51.014(a)(8) requires the denial of a jurisdictional challenge. In this case, none of the trial court’s orders on the parties’ cross-motions for summary judgment explicitly denied the relief sought in the section of Thomas’s motion for summary judgment challenging the trial court’s subject matter jurisdiction. However, the trial court’s rulings on the merits of some claims for which Thomas argued the trial court lacked subject matter jurisdiction constitute an implicit rejection of Thomas’s jurisdictional challenges. The Texas Rules of Appellate Procedure only require that the record show the trial court ruled on the request, objection, or motion, either expressly or implicitly. TEX. R. APP. P. 33.1(a)(2)(A). Because a trial court cannot reach the merits of a case without subject matter jurisdiction, Tex. Ass’n of Bus. v. Tex. Air Control Bd., 852 S.W.2d 440, 443 (Tex. 1993), a trial court that rules on the merits of an issue without explicitly rejecting an asserted jurisdictional attack has implicitly denied the jurisdictional challenge. See, e.g., Soberay Mach. & Equip. Co. v. MRF Ltd., 181 F.3d 759, 762 (6th Cir. 1999); Ahuna v. Dep’t of Hawaiian Home Lands, 64 Haw. 327, 640 P.2d 1161, 1165 n.9 (1982). By ruling on the merits of Long’s declaratory judgment claim, the trial court necessarily denied Thomas’s challenge to the court’s jurisdiction. That implicit denial satisfies section 51.014(a)(8) of the Texas Civil Practice and Remedies Code and gives the court of appeals jurisdiction to consider Thomas’s interlocutory *915appeal.28

The Executive Director also emphasizes a subsequent memorandum opinion from this Court in which we summarized the rule of Thomas as “a trial court that rules on the merits of an issue without explicitly rejecting an asserted jurisdictional attack has impliedly denied the jurisdictional challenge.”29 In that case, a suit for judicial review from an order of the Division of Workers Compensation, we applied Thomas to conclude that a trial-court order remanding the suit to the agency, made over a jurisdictional challenge raised through a plea to the jurisdiction and a summary-judgment motion, “necessarily denied [the] plea to the jurisdiction as well as [the] motion for summary judgment” notwithstanding the absence of an explicit ruling on the plea.30

The Executive Director views this case as a reprise of Thomas, urging that the district court’s order granting the Planning Commission’s motion for partial summary judgment and awarding it declaratory relief necessarily denied his jurisdictional challenges to that claim implicitly, a ruling that is in turn appealable under Section 51.014(a)(8). The Planning Commission seeks to distinguish Thomas by characterizing the partial summary judgment awarding it declaratory relief as something short of a determination on that claim’s “merits” in the sense Thomas contemplated and from which a denial of the Executive Director’s jurisdictional challenges can be implied. More critically, the Planning Commission suggests, the district court’s order explicitly deferring its ruling on the jurisdictional issue until trial belies any implied rejection of that challenge when granting the partial-summary-judgment motion and declaratory relief.

The Executive Director’s arguments in reliance on Thomas would present some potentially close, questions if the district court’s “Order Granting Plaintiffs Motion for Partial Summary Judgment” was viewed in isolation.31 However, our jurisdictional analysis must also take account of the district court’s subsequent “Order on Defendant’s Plea to Jurisdiction and Rule 91a Motion to Dismiss” because the Executive Director did not file his notice of appeal until after both orders were signed. In the latter order, the district court explicitly deferred the jurisdictional issue until trial, a decision that is squarely contrary to the unstated jurisdictional ruling that the Executive Director would have us *916imply from the earlier order under Thomas. And given that contradiction, we conclude, for two alternative reasons, that there is no basis for our jurisdiction under Section 51.014(a)(8).

The first alternative reason is perhaps the most obvious one—we should be hesitant to conclude that the district court impliedly denied the Executive Director’s jurisdictional challenge through its “Order Granting Plaintiffs Motion for Partial Summary Judgment” when its “Order on Defendant’s Plea to Jurisdiction and Rule 91a Motion to Dismiss” explicitly ruled otherwise.32 The two orders can both be given effect only by viewing the former as having granted the Planning Commission’s motion for partial summary judgment without reaching the jurisdictional grounds the Executive Director had asserted in opposition. Whatever this might imply about the correctness of the district court’s summary-judgment ruling, there would be no order subject to interlocutory appeal under Section 51.014(a)(8). Nor would the interlocutory summary-judgment ruling, in itself, be appealable.

Alternatively, the effect of the district court’s explicit deferral of its jurisdiction ruling would have been to vacate any jurisdictional ruling implicit in its summary-judgment order. It is in this regard that the sequence of the two orders, noted in our introduction, becomes significant. Both orders, being interlocutory, remained subject to change or modification—or being abrogated altogether—until merged into a final judgment.33 And because the “Order Granting Plaintiffs Motion for Partial Summary Judgment” preceded the “Order on Defendant’s Plea to Jurisdiction and Rule 91a Motion to Dismiss,” any implied jurisdictional ruling in the former would have been effectively vacated by the latter’s contrary reservation of jurisdictional issues until trial. Once again, there would be no order subject to appeal under Section 51.014(a)(8).

CONCLUSION

This litigation presents a number of potentially challenging legal questions for the Judiciary, and the broader policy and societal debates from which these arise may be more vexing still for the other two branches. But all of these matters presently lie beyond the subject-matter jurisdiction with which this Court is vested. Accordingly, we grant the Planning Commission’s motion and dismiss this appeal.