delivered the opinion of the Court.
Pursuant to Acts 1985, c. 620, and Acts 1986, cc. 250, 646, the people of this Commonwealth, at the general election held November 4, 1986, ratified an amendment to Va. Const, art. VI, § 1, which vested this Court with original jurisdiction “to answer questions of state law certified by a court of the United States or the highest appellate court of any other state.” By order entered January 16, 1987, we amended the Rules of this Court by adding Rule 5:42 which is appended to the foot of this opinion.
As contemplated by Rule 5:42(a) and (e), we entered an order March 18, 1987, accepting for consideration a question of law certified to us by orders entered in the above-captioned case by the United States District Court for the Eastern District of Virginia, Norfolk Division. The certification orders fully comply with the requirements of Rule 5:42(c) and (d), and we look to those orders for the facts and circumstances underlying the question certified.
As stated in the certification orders, the City of Norfolk and the School Board of the City of Norfolk (the plaintiffs) filed a civil complaint on June 27, 1986, seeking “compensatory and punitive *35damages allegedly sustained in inspecting, analyzing, containing, removing and replacing asbestos-containing products which they claim were placed in certain school buildings between 1939 and 1971.” The complaint, containing fifteen counts, demanded judgment against the manufacturers of the asbestos products, U.S. Gypsum, National Gypsum Company, W. R. Grace & Co. (the defendants), and Pfizer, Inc. At the time the question was certified to this Court, the complaint had been reduced to six counts claiming restitution, negligence, breach of express warranties, breach of implied warranties, fraud, and unfair trade practices. By stipulation, Pfizer, Inc., has been dismissed as a party-defendant.
In answer to the complaint, the defendants contended that the cause of action asserted by the plaintiffs was extinguished by Code § 8.01-250.1 In response, the plaintiffs contended that this statute merely barred the right of action, and that Code § 8.01-250.1 as amended effective April 6, 1986 by Acts 1986, c. 458,2 revived the right of action and extended the filing deadline to July 1, 1990. By rejoinder, the defendants filed a motion for partial summary judgment, contending that § 8.01-250 vests them with a property interest3 and that § 8.01-250.1 violates that part of the due process clause of the Constitution of Virginia, which provides *36that “no person shall be deprived of his . . . property without due process of law”.
Finding that the issue framed by the parties “may be determinative in this case” and that it is controlled by the Constitution and laws of this Commonwealth, the federal district court has certified the following question:
WHETHER THE APPLICATION OF VA. CODE § 8.01-250.1 TO THE FACTS PRESENTED HERE IS UNCONSTITUTIONAL UNDER THE DUE PROCESS CLAUSE OF ARTICLE I, SECTION 11 OF THE CONSTITUTION OF VIRGINIA.
In oral argument before this Court, the defendants advocated the affirmative of the question and the plaintiffs the negative. Although the question as certified does not implicate the federal Constitution, the plaintiffs argue that the due process clause of the Fourteenth Amendment and the due process clause of the Virginia Constitution are coextensive and, hence, that decisions of the United States Supreme Court are relevant to determination of the certified question. They cite Chase Securities Corp. v. Donaldson, 325 U.S. 304, 311 (1945), where the Court said:
In Campbell v. Holt, [115 U.S. 620 (1885)], this Court held that... a state legislature, consistently with the Fourteenth Amendment, may repeal or extend a statute of limitations, even after right of action is barred thereby, restore to the plaintiff his remedy, and divest the defendant of the statutory bar.
See also Electrical Workers v. Robbins & Myers, Inc., 429 U.S. 229, 243-44 (1976).
These decisions support the plaintiffs’ view that “statutes of limitation are procedural in nature” and that “there are no vested rights in procedural statutes” for purposes of the Fourteenth Amendment. But the federal decisions are inapposite to our inquiry. Code § 8.01-250 is not a procedural statute.
An ordinary statute of limitations is a procedural statute, one which creates a temporal bar to the maintenance of a legal remedy arising out of an accrued cause of action. Code § 8.01-250 is not a statute of limitations. In Virginia Military Institute v. King, 111 Va. 751, 758, 232 S.E.2d 895, 899 (1977), the plaintiff *37argued that the statutory precursor of Code § 8.01-250 was “the applicable statute of limitations”. In response to that argument, we said:
We do not agree. That statute sets an outside limit within which the applicable statutes of limitation operate. Its purpose is ... to establish an arbitrary termination date after which no litigation of the type specified may be initiated.
Id.
Although “statutes of limitations” and “statutes of repose” are terms sometimes loosely employed as interchangeable, they are, in fact, different in concept, definition, and function. As a general rule, the time limitation in a conventional statute of limitations begins to run when the cause of action accrues. We are of opinion the General Assembly intended Code § 8.01-250 to be a statute of repose. The time limitation in such a statute begins to run from the occurrence of an event unrelated to the accrual of a cause of action, and the expiration of the time extinguishes not only the legal remedy but also all causes of action, including those which may later accrue as well as those already accrued. Cheswold Vol. Fire Co. v. Lambertson Const., 489 A.2d 413, 421 (Del. 1985); see also Restatement (Second) of Torts § 899, comment g (1979). Conceptually, statutes of repose reflect legislative decisions that “as a matter of policy there should be a specific time beyond which a defendant should no longer be subjected to protracted liability. Thus a ‘statute of repose’ is intended as a substantive definition of rights as distinguished from a procedural limitation on the remedy used to enforce rights.” Stevenson, Products Liability and the Virginia Statute of Limitations — A Call for the Legislative Rescue Squad, 16 U. Rich. L. Rev. 323, 334 n.38 (1982). See generally McGovern, The Variety, Policy and Constitutionality of Product Liability Statutes of Repose, 30 Am. U. L. Rev. 579 (1981).
As a statute of repose, Code § 8.01-250 is a redefinition of the substantive rights and obligations of the parties to any litigation “arising out of the defective and unsafe condition of an improvement to real property”. Specifically, we think the lapse of the statutory period was meant to extinguish all the rights of a plaintiff, including those which might arise from an injury sustained later, see Deaconess Home Assn. v. Turner Constr., 14 Ohio App. *383d 281, 283-84, 470 N.E.2d 950, 954 (1984), and to grant a defendant immunity from liability for all the torts specified in the statute, see Harris v. Clinton Corn Processing Co., 360 N.W.2d 812, 816 (Iowa 1985).
The defendants contend that this legislative grant of immunity is a vested right and that they cannot be divested of that right by a statute enacted after the statutory period has expired.4 It is immaterial to our decision whether this right is characterized as “vested” or as “substantive”.
This Court has consistently held that the due process clause of the Virginia Constitution protects not only rights that have vested, but also substantive property interests which may ripen into vested rights. In Shiflet v. Eller, 228 Va. 115, 319 S.E.2d 750 (1984), the question on appeal was whether a tortfeasor’s potential right to contribution from a joint tort-feasor was entitled to due process protection. We noted that such a right arises at the time damage results from a joint tort and that such a right does not vest until one of the tort-feasors has paid an unfair share of the common obligation. We concluded that the right, although inchoate, is substantive, and we held that “ ‘substantive’ rights, as well as ‘vested’ rights, are included within those interests protected from retroactive application of statutes”, id. at 120, 319 S.E.2d at 753, because “[s]uch a retroactive application . . . would violate . . . due process rights and would be invalid”, id. at 121, 319 S.E.2d at 754,
Later, applying the rule in Shiflet, we said that “the retroactive application of a statute impairing a ‘substantive’ right violates due process and is therefore unconstitutional.” Potomac Hospital Corp. v. Dillon, 229 Va. 355, 360, 329 S.E.2d 41, 45, cert. denied, 474 U.S. 971 (1985). More recently in Bartholomew v. Bartholomew, 233 Va. 86, 353 S.E.2d 752 (1987), we held that “the ability of the non-settling tort-feasor to be released when the plaintiff has released another joint wrongdoer”, i.e., the right to invoke a defense, is also a substantive right and that the retroac*39tive application of a statute impairing that right was “constitutionally invalid”. Id. at 91, 353 S.E.2d at 755, 756.
Like the rights of those joint tort-feasors (which arose when the tort was committed), the rights bestowed by Code § 8.01-250 upon the defendants in this case (which arose when the statutory period expired) are substantive if not vested and, as such, may not be impaired by retroactive application of Code § 8.01-250.1.
The plaintiffs argue that, even if Code § 8.01-250.1 offends the due process clause, we should hold that it is constitutionally sufficient as an exercise of the police power.
The plaintiffs seem to assume that any legislative act which facilitates governmental efforts to reduce a hazard to public health, safety, morals, or general welfare is exempt from constitutional constraints. True, all legislative enactments are entitled to a presumption of constitutionality, but a statute premised upon the police power “is subject to the constitutional guarantee that no property shall be taken without due process of law and where the police power conflicts with the Constitution the latter is supreme”. Board of Supervisors v. Carper, 200 Va. 653, 660, 107 S.E.2d 390, 395 (1959). “[T]he police power is ‘elastic’. But its stretch is not infinite. If it were, no property right, indeed, no personal right, could co-exist with it.” Bd. Sup. James City County v. Rowe, 216 Va. 128, 139, 216 S.E.2d 199, 209 (1975); accord Cupp v. Board of Supervisors, 227 Va. 580, 594-96, 318 S.E.2d 407, 414-15 (1984); see also Nollan v. California Coastal Commission, 483 U.S. __, 107 S.Ct. 3141 (1987).
We agree that, subject to constitutional guarantees, the legislature’s police power includes the power to enact a statute reasonably designed to protect society against the health hazard posed by asbestos products installed in buildings frequented by the public at large. See Alford v. Newport News, 220 Va. 584, 260 S.E.2d 241 (1979). But Code § 8.01-250.1 is not such a statute.
As the plaintiffs say, current Environmental Protection Agency regulations “require school districts to remove asbestos materials prior to any substantial renovation or demolition of a building.” Without the benefit of the revival statute, the cost of compliance with these regulations would have to be paid out of the public treasury. It appears, therefore, that the revival statute was designed primarily, not to relieve the hazard to public health, but to relieve budgetary concerns. Such a statute cannot survive *40the defendants’ due process challenge, and we reject the plaintiffs’ police power argument.
On brief, the plaintiffs raise other issues. Specifically, they argue that the fraudulent-concealment count alleged in their complaint seeks equitable relief; that Code § 8.01-250, the statute of repose, does not apply to that count because laches is the only bar to a suit in equity; and, hence, that their complaint was timely filed. Further, they contend that their action at law for fraud was timely filed because, they say, the running of the five-year period specified in the statute of repose is tolled by the alleged fraudulent concealment.
Because both issues are patently outside the compass of the question certified, we will not notice either. Responding definitively to the question before us, we hold that the application of Code § 8.01-250.1 to the facts presented in the orders of certification is unconstitutional under the due process clause of Va. Const, art. I, § 11.
Certified question answered in the affirmative.
WHITING, J., dissenting.
*41APPENDIX
Rule 5:42. Certification Procedures
(a) Power to Answer. — The Supreme Court may in its discretion answer questions of law certified to it by the Supreme Court of the United States, a United States court of appeals for any circuit, a United States district court, or the highest appellate court of any state or the District of Columbia. Such answer may be furnished, when requested by the certifying court, if a question of Virginia law is determinative in any proceeding pending before the certifying court and it appears there is no controlling precedent on point in the decisions of the Supreme Court or the Court of Appeals of Virginia.
(b) Method of Invoking. — This Rule may be invoked only by an order of one of the courts referred to in section (a). No party litigant in the foregoing courts may file in the Supreme Court a petition or motion for certification.
(c) Contents of Certification Order. — A certification order shall set forth:
(1) the nature of the controversy in which the question arises;
(2) the question of law to be answered;
(3) a statement of all facts relevant to the question certified;
(4) the names of each of the parties involved;
(5) the names, addresses, and telephone numbers of counsel for each of the parties involved;
(6) a brief statement explaining how the certified question of law is determinative of the proceeding in the certifying court; and
(7) a brief statement setting forth relevant decisions, if any, of the Supreme Court and the Court of Appeals of Virginia and the reasons why such decisions are not controlling.
(d) Preparation of Certification Order. — The certification order shall be prepared by the certifying court, signed by the presiding justice or judge, and forwarded to the Supreme Court by the clerk of the certifying court under its official seal. The Supreme Court may require the original or copies of all or of any portion of the record before the certifying court to be filed with the certification order, if, in the opinion of the Supreme Court, the record or portion thereof may be necessary in answering the certified question. The Supreme Court may in its discretion restate any question of law certified or may request from the certifying court addi*42tional clarification with respect to any question certified or with respect to any facts.
(e) Notification of Acceptance or Rejection. — The Supreme Court, in its discretion, may decide whether to answer any certified question of law. The Supreme Court will notify the certifying court and counsel for the parties of its decision to accept or to reject any certified question of law. A notice accepting a question will include a briefing schedule and, if oral argument is permitted by the Supreme Court, a tentative date and the length of time allowed for such argument.
(f) Revocation of Acceptance. — The Supreme Court, in its discretion, may revoke its decision to answer a certified question of law at any time. Upon deciding to revoke, the Supreme Court will notify the certifying court and counsel for the parties of its action.
(g) Costs of Certification. — Fees and costs shall be the same as in civil appeals docketed in the Supreme Court and shall be paid as ordered by the certifying court in its order of certification.
(h) Briefs. — The form, length, and time for submission of briefs shall comply with Rules 5:26 through 5:34 mutatis mutandis.
(i) Opinion. — A written opinion of the Supreme Court stating the law governing each question certified will be rendered as soon as practicable after the submission of briefs and after any oral argument. The opinion will be sent by the clerk under the seal of the Supreme Court to the certifying court and to counsel for the parties and shall be published in the Virginia Reports.
In relevant part, Code § 8.01-250 provides as follows:
No action to recover for any injury to property, real or personal, or for bodily injury or wrongful death, arising out of the defective and unsafe condition of an improvement to real property, nor any action for contribution or indemnity for damages sustained as a result of such injury, shall be brought against any person performing or furnishing the design, planning, surveying, supervision of construction, or construction of such improvement to real property more than five years after the performance of furnishing of such services and construction.
Code § 8.01-250.1 provides in full:
Notwithstanding the provisions of § 8.01-234 or any other section in this chapter, every action against a manufacturer or supplier of asbestos or material containing asbestos brought by or on behalf of any agency of the Commonwealth incorporated for charitable or educational purposes; counties, cities or towns; or school boards, to recover for (i) removal of asbestos or materials containing asbestos from any building owned or used by such entity, (ii) other measures taken to correct or ameliorate any problem related to asbestos in such building or (iii) reimbursement for such removal, correction or amelioration which would otherwise be barred prior to July 1, 1990, as a result of expiration of the applicable period of limitation, is hereby revived or extended. Any action thereon may be commenced prior to July 1, 1990.
Code § 8.01-250 applies to manufacturers of building materials. Cape Henry v. Natl. Gypsum, 229 Va. 596, 331 S.E.2d 476 (1985).
The defendants insist that, even if Code § 8.01-250 is denominated a statute of limitations, once the period of limitations has expired, the right to assert the defense of the statute is a vested right. Although we recognize the logic of that argument, see Johnston v. Gill, 68 Va. (27 Gratt.) 587, 595 (1876) (dicta); Kesterson v. Hill, 101 Va. 739, 45 S.E. 288 (1903); Strickland v. Simpkins, 221 Va. 730, 734, 273 S.E.2d 539, 541 (1981), we need not decide that question.