The central issue raised on appeal is a question of sequence or ordering: whether the district court should have first addressed Appellant University of South' Alabama’s (“University”) Motion to Remand this diversity case to state court because it lacked subject matter jurisdiction before it turned its attention to the Attorney General of Ala *408 bama’s Notice of Dismissal under Fed. R.Civ.P. 41(a)(1).. Because the district court plainly lacked subject matter jurisdiction to entertain this case, we hold that it improvidently reached a complex question of substantive state law — -whether the Attorney General had the power to manage and control complex litigation commenced by the University. Accordingly, we vacate its order of dismissal and remand to the district court with instructions that this cause be remanded to the state court from whence it came.
I.
Appellant University commenced this action on May 19, 1997 in the Circuit Court of Mobile County, Alabama, against Appellees The American Tobacco Company, American Brands, Inc. (now known as Fortune Brands, Inc.), R.J. Reynolds Tobacco Company, RJR Nabisco, Inc., Batus Tobacco Services, Inc., BAT Industries, P.L.C., British American Tobacco Company, Ltd., Brown & Williamson Tobacco Corporation, Philip Morris Inc. (Philip Morris U.S.A.), Loews Corporation, Lorillard Corporation, The Council for Tobacco Research-U.S.A., Inc. (successor to Tobacco Institute Research Committee), The Tobacco Institute, Inc., Hill & Knowlton, Inc., United States Tobacco Company, and fictitious defendants “A” through “Z” to recover damages for and restitution of the monies expended for unreimbursed medical care arising from tobacco-related illnesses. Specifically, the University brought claims for restitution, unjust enrichment, indemnity, public nuisance, fraud and misrepresentation, conspiracy, and antitrust violations.
On June 17, 1997, Appellees removed the action to federal district court on the basis of diversity jurisdiction. See 28 U.S.C. §§ 1332, 1441 (1994). The following day, June 18, 1997, Appellee R.J. Reynolds filed its answer. Almost immediately thereafter, on June 23, 1997, before any other Appellee had answered, the Attorney General of Alabama filed a Notice of Dismissal pursuant to Fed.R.Civ.P. 41(a)(1). The Attorney General argued that he was the proper plaintiff in this action because the University is an agency and instrumentality of the state subject to the Attorney General’s authority to direct and control litigation under Ala.Code § 36-15-21 (1991 & Supp.1997). The University then filed a Motion to Remand on June 26,1997, alleging lack of subject matter jurisdiction. On July 7, 1997, Appellee R.J. Reynolds filed a “Joinder in Defendants’ Memorandum of Law” requesting dismissal by order of the court pursuant to Fed. R.Civ.P. 41(a)(2).
On August 12, 1997, after conducting a hearing on the matter, the district court issued a lengthy final order finding that since the Attorney General had authority under Alabama’law to file a Notice of Dismissal in this action, the entire action was dismissed without prejudice pursuant to Fed. R.Civ.P. 41(a)(1). Specifically, the district court found that the Notice of Dismissal filed by the Attorney General immediately dismissed the case as to all Appellees other than R.J. Reynolds Tobacco Company, which previously had filed an answer. See Fed. R.Civ.P. 41(a)(1)(i). The district court concluded, however, that the dismissal also was effective as to R.J. Reynolds on July 7, 1997, when the company filed a signed pleading concurring with the Attorney General’s Notice of Dismissal. See Fed.R.Civ.P. 41(a)(1)(h). At no point did the court reach the question of its subject matter jurisdiction. This appeal followed. 1
II.
We review issues of federal subject matter jurisdiction
de novo. See Stovall v. City of Cocoa,
*409 A.
Under Rule 41(a)(1), “an action may be dismissed by the plaintiff without order of the court (i) by filing a notice of dismissal at any time before service of the adverse party of an answer or of a motion for summary judgment, whichever first occurs, or (ii) by filing a stipulation of dismissal signed by all parties who have appeared in the action.” Fed.R.Civ.P. 41(a)(1). Ordinarily, a Rule 41(a)(1) voluntary dismissal is effective immediately and requires no action by the district court.
See Matthews,
In the instant case, however, the Attorney General’s Notice of Dismissal demanded more than a perfunctory voluntary dismissal analysis. Rather, the notice necessarily required the district court to determine a complex substantive issue of Alabama law. Because the Alabama Attorney General was neither a named plaintiff, nor counsel of record, it was by no means clear that the proper plaintiff had filed a Notice of Dismissal in this proceeding — particularly where the University vigorously contested the Attorney General’s power to speak for the plaintiff. Therefore, in order to determine whether the Attorney General’s notice satisfied the requirements of Rule 41(a)(1), the district court first had to determine that the University was an agency of the state, that the University was subject to the authority of the Attorney General to control all litigation in the state, and, hence, that the Attorney General had the authority to file a Notice of Dismissal. Plainly, these were substantive rulings concerning Alabama law, albeit unusual in a Rule 41(a)(1) context, that the district court had no authority to make without first determining whether it had subject matter jurisdiction to hear the case. Accordingly, because of the unusual circumstances of the instant case, we conclude that the district court erred in failing to consider Appellant’s Motion to Remand for lack of subject matter jurisdiction before it addressed the Attorney General’s Notice of Dismissal.
It is by now axiomatic that the inferior federal courts are courts of limited jurisdiction. They are “empowered to hear only those cases within the judicial power of the United States as defined by Article III of the Constitution,” and which have been entrusted to them by a jurisdictional grant authorized by Congress.
Taylor v. Appleton,
Accordingly, “[w]hen a federal court acts outside its statutory subject-matter jurisdiction, it violates the fundamental constitutional precept of limited federal power.”
Id.
(citing
Oliver v. Trunkline Gas Co.,
A necessary corollary to the concept that a federal court is powerless to act without jurisdiction is the equally unremarkable principle that a court should inquire into whether it has subject matter jurisdiction at the earliest possible stage in the proceedings. Indeed, it is well settled that a federal court is obligated to inquire into subject matter jurisdiction
sua sponte
whenever it may be lacking.
See Fitzgerald v. Seaboard Sys. R.R.,
We add that our removal jurisdiction is no exception to a federal court’s obligation to inquire into its own jurisdiction. Pursuant to 28 U.S.C. § 1441(a) (1994), “[a]ny civil action brought in a State court of which the district courts of the United States have original jurisdiction, may be removed by the defendant or the defendants, to the district court of the United States for the district and division embracing the place where such action is pending.” Therefore, when an action is removed from state court, the district court first must determine whether it has original jurisdiction over the plaintiffs claims.
See Cabalceta v. Standard Fruit Co.,
However, “[i]f at any time before final judgment it appears that the district court lacks subject matter jurisdiction, the case shall be remanded” to the state court from' whence it came. 28 U.S.C. § 1447(c). This provision is mandatory and may not be disregarded based on speculation about the proceeding’s futility in state court.
See International Primate Protection League v. Administrators of Tulane Educ. Fund,
Because removal jurisdiction raises significant federalism concerns, federal courts are directed to construe removal statutes strictly.
See Shamrock Oil & Gas Corp. v. Sheets,
In the instant case, the district court should have resolved the issue of subject matter jurisdiction before reaching the merits of any other issue, particularly where so important and complicated a question of state law involving the power of Alabama’s Attorney General was at stake. Although a Notice of Dismissal pursuant to Rule 41(a)(1) normally does not present this concern, the district court unquestionably determined the scope of the Attorney General’s authority under Alabama law without first confirming its own jurisdiction to entertain the case. We believe that this course was neither prudent nor supported by principles of comity. Indeed, because the district court was in fact without subject matter jurisdiction, see infra, the court’s ruling was in essence an advisory opinion. In sum, the district court erred in failing to first address its power to act.
B.
Turning to the merits of the jurisdictional issue, the University of South Alabama is not a citizen of Alabama for the purpose of diversity of citizenship, and as such, Appellant’s claims were improvidently removed. The burden of establishing subject
*412
matter jurisdiction falls on the party invoking removal.
See Pacheco de Perez v. AT & T Co.,
In the context of Eleventh Amendment immunity, we have held that state universities are “agencies or instrumentalities” of the state, and thus are immune from suit in federal court.
Harden v. Adams,
Based on this unambiguous precedent, we conclude that the University is an instrumentality of the state, not a citizen of the state of Alabama, for the purpose of diversity jurisdiction. Therefore, Appellees have failed to establish subject matter jurisdiction to support their removal of Appellant’s claims. We add, in light of the significant federalism concerns raised by removal and the principle that all doubts about jurisdiction should be resolved in favor of remand, see supra, that it would be more prudent to remand this case pursuant to 28 U.S.C. § 1447(e) and provide the state court with the opportunity to resolve this unique and complicated question of state law.
III.
Since the district court lacked subject matter jurisdiction over this action, it was without authority to rule on the efficacy of the Attorney General’s Notice of Dismissal. Accordingly, the order of the district court must be and is VACATED and this matter is REMANDED to the district court with in *413 structions to remand this action to the state court from whence it came.
Notes
. Rule 41(a)(1) voluntary dismissal without prejudice is not ordinarily appealable.
See Construction Aggregates, Ltd. v. Forest Commodities Corp.,
. In
Bonner v. City of Prichard,
