The central issue before this Court on appeal is whether the trial court erred in denying the defendant’s motion to dismiss the charge upon which he was tried for second degree murder; his motion to dismiss was based on the common law year and a day rule. Although today we prospectively abrogate the year and a day rule, we conclude that the trial court erred and that the decision of the Court of Appeals finding no error must be reversed. We further conclude that the judgment against the defendant for second degree murder must be vacated and this case remanded for judgment as upon a verdict for involuntary manslaughter.
The State’s evidence tended to show that the defendant drank beer with friends at a Winston-Salem bar from 5:00 p.m. until shortly before midnight on 10 March 1987. During that period, the defendant was seen drinking at least four beers. He then drove with a friend from the bar to the friend’s home, approximately a mile and a half from the bar. The defendant started to take his other passenger, Bobby Caddell, home.
Shortly after midnight, Lanny Lee Bradley and his wife were traveling west on Union Cross Road in a pickup truck. The car driven by the defendant crossed over into the oncoming lane of traffic, where the car struck the Bradleys with such force that it split in half and its front section traveled 170 feet after impact. Union Cross Road is a rural, paved highway running east and west with a posted speed limit of fifty-five miles per hour.
Bobby Caddell’s body was found lying in the westbound lane of the road. Mrs. Bradley was buried under wreckage from the collision, and she was barely breathing. She was later pronounced dead at the scene of the accident. Lanny Lee Bradley was pinned in his truck, having difficulty breathing. He was given emergency treatment at the accident scene and transported to the hospital.
Deputy L. E. Gordon of the Forsyth County Sheriff’s Department arrived shortly after the collision. He went to the front section of the defendant’s car, which was overturned with the defendant inside. Deputy Gordon removed the defendant from the car. The defendant had sustained injuries to his head and knees and had a strong smell of alcohol on his breath. Gordon then went to determine if he could assist the Bradleys. When Gordon turned around, the defendant was gone.
*616Meanwhile, the defendant had hitched a ride from two individuals who detected a strong odor of alcohol on his breath. They took him to his mother’s home. Shortly after 1:00 a.m., the defendant was taken from his mother’s home by ambulance to the hospital. When questioned about what had caused his injuries, the defendant stated, “I guess because I had a wreck.” The results of a test performed on blood drawn from the defendant at 2:29 a.m. showed an alcohol content of 0.104 grams per 100 milliliters of blood.
Lanny Lee Bradley experienced a severe head injury as a result of the collision with the defendant. In addition to a tube placed in his windpipe to enable him to breathe, he received intravenous fluids to raise his blood pressure. A CAT scan, done at the hospital, showed severe swelling of his brain.
Lanny Lee Bradley remained totally unconscious in the intensive care neurological ward for four months, completely dependent upon life support systems. He was moved from intensive care when his vital signs stabilized. Occasionally, he would open his eyes and appear to look around, but he never regained consciousness beyond that point. While hospitalized, he was connected to a ventilator for oxygen and was given fluid intravenously. He was also given medication to prevent a.ny seizures due to the head injury. On 3 May 1988, he died from respiratory failure and bacterial pneumonia — both of which related to his head injury.
At trial, the jury returned a verdict finding the defendant guilty of the second degree murder of Lanny Lee Bradley. The trial court entered’ judgment on that verdict and sentenced the defendant to a twenty-year term of imprisonment.
On appeal to the Court of Appeals, the defendant contended, inter alia, that the murder charge against him should have been dismissed under the common law “year and a day” rule because uncontroverted evidence showed that Bradley had died fourteen months after the collision. The Court of Appeals rejected the defendant’s contention and held that his trial was free from prejudicial error. On 27 July 1990, this Court allowed the defendant’s petition for discretionary review, limited to the issue of the applicability of the year and a day rule.
 Before addressing the defendant’s assignment of error, a review of the history of the “year and a day” rule is helpful. Our General *617Assembly has declared that so much of the common law as has not been abrogated or repealed by statute or become obsolete is in full force and effect in this state. N.C.G.S. § 4-1 (1986); see, e.g., State v. Buckom, 328 N.C. 313, 401 S.E.2d 362 (1991); Martin v. Thornburg, 320 N.C. 533, 359 S.E.2d 472 (1987); McMichael v. Proctor, 243 N.C. 479, 91 S.E.2d 231 (1956); State v. Hampton, 210 N.C. 283, 186 S.E. 251 (1936). The “common law” referred to in N.C.G.S. § 4-1 is the common law of England as of the date of the signing of the Declaration of Independence. Buckom, 328 N.C. 313, 401 S.E.2d 362; Hall v. Post, 323 N.C. 259, 372 S.E.2d 711 (1988); Steelman v. City of New Bern, 279 N.C. 589, 184 S.E.2d 239 (1971).
Under the common law of England, a killing was not murder unless the death of the victim occurred within a year and a day of the act inflicting injury. 4 W. Blackstone, Commentaries *197; see H. Broom, Commentaries on the Common Law *935 (1856). Otherwise, the loss of life would be attributed to natural causes rather than the distant act inflicting injury. R. Perkins & R. Boyce, Criminal Law 46 (3d ed. 1982). This requirement envisioned that the death must be shown to be “sufficiently connected with the act.” 3 W. Holdsworth, A History of English Law 315 (3d ed. 1923).
Our research discloses that the origins of the rule are generally traced to the thirteenth century. The statute which may have led to the evolution of the rule reads as follows:
An Appeal of Murther .... (4) It is provided also, that no Appeal shall be abated so soon as they have been heretofore; but if the appellor declare the Deed, the Year, the Day, the Hour, the Time of the King, and the Town where the Deed was done, and with what Weapon he was slain, the Appeal shall stand in Effect, (5) and shall not be abated for Default of fresh Suit, if the Party shall sue within the Year and the Day after the Deed done.
Statutes of Gloucester, 6 Edw. I, c. IX (1278); see State v. Hefler, 310 N.C. 135, 310 S.E.2d 310 (1984). The year and a day time period which found its way into the criminal law may have been “connected with the fact that it was the length of time within which the relatives” of the victim could bring the “appeal of death” they were entitled to bring as private citizens. 3 W. Holdsworth, supra, at 315; see State v. Hefler, 310 N.C. 135, 310 S.E.2d 310 (1984). But cf. United States v. Jackson, 528 A.2d 1211 (D.C. 1987) *618(“Since the origins and purposes of the rule are obscure, we cannot say with certainty why the rule came into existence.”). The appeal of death or “appeal of Murther” recognized by the ancient common law and referred to in the Statutes of Gloucester “was a private and vindictive process by an interested party . . . which grew out of the old Germanic custom of ‘weregild’, or compensation for the death.” Commonwealth v. Ladd, 402 Pa. 164, 167, 166 A.2d 501, 503 (1960). It is notable that appeals of death, rather than prosecutions for murder, were contemplated under the Statutes of Gloucester. Id. It appears that only Coke, among the commentators on the common law of England, states that “the rule is said to run from the death both in public prosecutions for murder and in private appeals of death.” Id. at 167-68, 166 A.2d at 503. As applied in American courts, however, the year and a day rule generally has been viewed to have applied in public prosecutions and to have “operated like an ordinary statute of limitations.” Commonwealth v. Lewis, 381 Mass. 411, 413, 409 N.E.2d 771, 772 (1980), cert. denied, 450 U.S. 929, 67 L. Ed. 2d 360 (1981). But see People v. Mudd, 154 Ill. App. 3d 808, 812, 507 N.E.2d 869, 872 (1987) (“[T]he ‘year and a day rule’ did not operate in the nature of a statute of limitations barring prosecution. So long as the death occurred within the specified time frame, it was then presumed the blow or injury caused the death for purposes of a homicide prosecution.”). There is some “suggestion that the rule was intended to simply soften the old brutal law regarding homicides.” Lewis, 381 Mass, at 414, 409 N.E.2d at 773. There is also support for the proposition that the rule was created by judges due to the uncertainty of medical science in determining the cause of death when the death occurs so long after the injury. See Hefler, 310 N.C. at 140, 310 S.E.2d at 313; W. LaFave & A. Scott, Criminal Law § 3.12(i) (2d ed. 1986).
The common law year and a day rule, as it has been applied in murder cases in North Carolina, was first stated by this Court in State v. Orrell, 12 N.C. (1 Dev.) 139 (1826). There, we said that “if death did not take place within a year and a day of the time of receiving the wound, the law draws the conclusion that it was not the cause of death; and neither the court nor jury can draw a contrary one. . . . For if death happened beyond that time, the law would presume that it proceeded from some other cause than the wound.” Id. at 141. Subsequently, the validity of the rule has been recognized by this Court in five murder cases. *619 State v. Pate, 121 N.C. 659, 28 S.E. 354 (1897); State v. Morgan, 85 N.C. 581 (1881); State v. Haney, 67 N.C. 467 (1872); State v. Baker, 46 N.C. (1 Jones) 267 (1854); State v. Shepherd, 30 N.C. (8 Ired.) 195 (1847).
In Hefler, we refused to apply the year and a day rule to involuntary manslaughter cases but expressly left open the issue of whether it should continue to apply in murder cases. 310 N.C. at 141, 310 S.E.2d at 313. There, in a scholarly opinion by Justice Martin, we took judicial notice of significant advances in both medical science and crime detection, as well as the fact that these advances have resulted in sophisticated medical tests, analyses, and diagnoses that allow positive evidence to be presented to a jury on questions of causation in criminal prosecutions. Hefler, 310 N.C. at 140, 310 S.E.2d at 313.
 We now conclude that, whether we choose to view the year and a day rule as derived from limitations placed upon appeals of death by ancient law or as arising from concerns about the limitations of medical science, any rationale for the rule is anachronistic today. Therefore, we conclude that the year and a day rule has become “obsolete,” within the meaning of that term as used in N.C.G.S. § 4-1, and declare that the rule is no longer part of the common law of North Carolina for any purpose. In so doing, we follow the clear modern trend in other jurisdictions to abrogate the rule. W. LaFave & A. Scott, Criminal Law 299 (2d ed. 1986); R. Perkins & R. Boyce, Criminal Law 47 (3d ed. 1982); see United States v. Jackson, 528 A.2d 1211, 1220 (D.C. 1987) (“Since the origin and rationale for the year and a day rule are hazy, and the generally acknowledged reason for the rule now appears highly suspect, we deem judicial abolition of the judicially-created rule appropriate.”); Commonwealth v. Lewis, 381 Mass. 411, 418, 409 N.E.2d 771, 775 (1980) (footnote omitted) (“We share the view that the rule is no longer supportable in reason, and that its relegation to the shades of history may be accomplished by court decision.”), cert. denied, 450 U.S. 929, 67 L. Ed. 2d 360 (1981); People v. Stevenson, 416 Mich. 383, 394, 331 N.W.2d 143, 147 (1982) (“rule has outlived its usefulness”); State v. Sandridge, 5 Ohio Op. 419, 421, 365 N.E.2d 898, 899 (1977) (“Today, the retention of the ‘year and a day rule’ is clearly an anachronism.”); State v. Hudson, 56 Or. App. 462, 642 P.2d 331 (1982) (“rule is no longer applicable”); Commonwealth v. Ladd, 402 Pa. 164, 173, 166 A.2d 501, 506 (1960) (“There is now no more reason for a rule of a *620year and a day than there is for one of a hundred days or a thousand and one nights.”); State v. Pine, 524 A.2d 1104, 1107 (R.I.1987) (“[T]he long life of the rule may result from the infrequency with which the issue has been raised. Courts, therefore have not been given the opportunity to address it.”); State v. Edwards, 104 Wash. 2d 63, 69, 701 P.2d 508, 511 (1985) (“Medical science has progressed to such a degree it makes little sense to have a rule which requires death to occur within a particular time to resolve issues of causation.”). But see State v. Minster, 302 Md. 240, 245, 486 A.2d 1197, 1199 (1985) (“[W]e believe it is the legislature which should mandate any change in the rule, if indeed any change is appropriate.”).
The defendant recognizes that this Court may abrogate the common law year and a day rule, but argues that we may do so only prospectively. He contends that any change in the application of the rule would amount to an unconstitutional ex post facto law, if applied to his case. Both our state and federal constitutions forbid the enactment of ex post facto laws. U.S. Const. art. I, § 10; N.C. Const, art. I, § 16. Since its earliest decisions, the Supreme Court of the United States has defined an ex post facto law as one which (1) makes an action criminal which was done before the passing of the law and which was innocent when done, (2) aggravates a crime or makes it greater than when it was committed, (3) allows imposition of a different or greater punishment than was permitted when the crime was committed, or (4) alters the legal rules of evidence to permit different or less testimony to convict the offender than was required at the time the offense was committed. Calder v. Bull, 3 U.S. (3 Dall.) 386, 390, 1 L. Ed. 648, 650 (1798). That Court has also stated that “two critical elements must be present for a criminal or penal law to be ex post facto: it must be retrospective, that is, it must apply to events occurring before its enactment, and it must disadvantage the offender affected by it.” Weaver v. Graham, 450 U.S. 24, 29, 67 L. Ed. 2d 17, 23 (1981).
Although the ex post facto clauses are directed specifically at legislative action, the Supreme Court of the United States has held that the fifth and fourteenth amendments to the Constitution of the United States also forbid retroactive application of an unforeseeable judicial modification of criminal law, to the disadvantage of the defendant. Marks v. United States, 430 U.S. 188, 191-92, 51 L. Ed. 2d 260, 264-65 (1977); Bouie v. City of Columbia, 378 *621U.S. 347, 355, 12 L. Ed. 2d 894, 900 (1964); accord State v. Waddell, 282 N.C. 431, 446, 194 S.E.2d 19, 29 (1973) (“[T]he constitutional ban against the retroactive increase of punishment for a crime applies as well against judicial action having the same effect.”). But see State v. Cooper, 304 N.C. 701, 705, 286 S.E.2d 102, 104 (1982) (“Decisions are presumed to operate retroactively, and overruling decisions are given solely prospective application only when there is compelling reason to do so.”); State v. Rivens, 299 N.C. 385, 392, 261 S.E.2d 867, 871 (1980) (citation omitted) (“There is no violation of the ex post facto clause in the United States Constitution when a decision is applied retroactively because the clause applies to legislative and not judicial action. ... A party has no vested right in a decision of this Court.”).
Although not a controlling consideration, we note that of the six courts which since 1960 have judicially abolished the year and a day rule, five have given their decisions prospective effect only. United States v. Jackson, 528 A.2d 1211 (D.C. 1987); Commonwealth v. Lewis, 381 Mass. 411, 409 N.E.2d 771 (1980), cert. denied, 450 U.S. 929, 67 L. Ed. 2d 360 (1981); People v. Stevenson, 416 Mich. 383, 331 N.W.2d 143 (1982); State v. Young, 77 N.J. 245, 390 A.2d 556 (1978); State v. Pine, 524 A.2d 1104 (R.I. 1987). Contra Commonwealth v. Ladd, 402 Pa. 164, 166 A.2d 501 (1960) (abrogation of rule applied retroactively). We conclude that the prohibitions against ex post facto laws embodied in the fifth and fourteenth amendments to the Constitution of the United States require that we give this decision abolishing the year and a day rule prospective effect only. As a result, the defendant’s conviction for second degree murder must be deemed to be error.
[3, 4] In Orrell, the first case in which this Court applied the year and a day rule, it was held that where the death of the deceased occurred more than a year and a day after the defendant shot him, the defendant could not be held guilty of the murder of the deceased. 12 N.C. (1 Dev.) at 141. When Orrell was decided in 1826, no degrees of murder were known to the law. Prior to 1893, the common law definition of murder applied and simply made all intentional and unlawful killings of human beings with malice aforethought, express or implied, murder. State v. Davis, 305 N.C. 400, 290 S.E.2d 574 (1982); State v. Rhyne, 124 N.C. 847, 33 S.E. 128 (1899). In 1893, the General Assembly enacted 1893 N.C. Pub. Laws ch. 85, the terms of which are now embodied in N.C.G.S. § 14-17. That statute classifies murders as either first *622or second degree, but only for purposes of assigning punishment; it does not define or redefine the crime of murder. Davis, 305 N.C. at 422-23, 290 S.E.2d at 588; State v. Streeton, 231 N.C. 301, 305, 56 S.E.2d 649, 652 (1949). It is well settled that when a statute addresses a crime known at common law without otherwise defining it, the common law definition of the crime applies. Buckom, 328 N.C. 313, 401 S.E.2d 362; State v. Roberts, 286 N.C. 265, 210 S.E.2d 396 (1974); State v. Ingland, 278 N.C. 42, 178 S.E.2d 577 (1971). This Court has often held that, as N.C.G.S. § 14-17 does not define the crime of murder, the definition of that crime remains the same as it was at common law when Orrell was decided. E.g., Davis, 305 N.C. at 422-23, 290 S.E.2d at 588; Streeton, 231 N.C. at 305, 56 S.E.2d at 652. That common law definition of any intentional and unlawful killing of a human being with malice aforethought, express or implied, as murder includes all murders now divided by the statute into first and second degree murder for purposes of punishment. State v. Smith, 221 N.C. 278, 289-90, 20 S.E.2d 313, 320-21 (1940). Therefore, the year and a day rule applied to the crime of murder in Orrell applied equally to all murders which, for purposes of punishment only, are today divided into first degree murders and second degree murders. In fact, this Court noted in one of its earliest reported cases on the subject of the year and a day rule as applied in North Carolina that: “Unless the death occurs within the year and day after the stroke [inflicted on the victim by the defendant], there is no felonious killing.” State v. Baker, 46 N.C. (1 Jones) 267, 273 (1854) (emphasis added). Accordingly, under our prior cases, the defendant could not be found guilty of murder in the present case, as the victim died more than a year and a day after the injury was inflicted upon him by the defendant.
To apply today’s decision abrogating the year and a day rule to permit the defendant to be convicted of murder in the present case would, at the very least, permit his conviction upon less evidence than would have been required to convict him of that crime at the time the victim died and would, for that reason, violate the principles preventing the application of ex post facto laws. Calder, 3 U.S. (3 Dall.) at 390, 1 L. Ed. at 650. Retroactive application of our decision today, so as to uphold the judgment for murder in the present case, clearly would be to apply this decision to events occurring before this decision and severely disadvantage the defendant; to do so would violate the principle emanating from *623the fifth and fourteenth amendments to the Constitution of the United States forbidding retroactive application of an unforeseeable judicial modification of criminal law. Marks, 430 U.S. at 191-92, 51 L. Ed. 2d at 264-65; Bouie, 378 U.S. at 355, 12 L. Ed. 2d at 900. Therefore, the judgment against the defendant for second degree murder must be vacated.
At the time the defendant struck the victim in the present case and at the time the victim died, however, we had made it clear that the year and a day rule would not be applied to involuntary manslaughter cases. Hefler, 310 N.C. at 141, 310 S.E.2d at 313. Therefore, the defendant concedes that the rule would not have prevented his being convicted and sentenced for involuntary manslaughter. In the present case, the trial court submitted possible verdicts finding the defendant guilty of second degree murder, guilty of the lesser included offense of involuntary manslaughter or not guilty. The jury convicted the defendant of second degree murder, and the judgment for second degree murder which we hold must be vacated was entered upon that verdict. In finding the defendant guilty of second degree murder, however, the jury necessarily had to find facts establishing the lesser included offense of involuntary manslaughter. See State v. Greene, 314 N.C. 649, 336 S.E.2d 87 (1985). Hence, leaving the jury’s verdict undisturbed but recognizing it for what it is, this case will be remanded for judgment as upon a verdict of guilty of involuntary manslaughter. See State v. Freeman, 307 N.C. 445, 298 S.E.2d 376 (1983); State v. Dawkins, 305 N.C. 289, 287 S.E.2d 885 (1982); State v. Jolly, 297 N.C. 121, 130, 254 S.E.2d 1, 7 (1979).
The decision of the Court of Appeals finding no error in the trial and judgment against the defendant for second degree murder is reversed. This case is remanded to the Court of Appeals for its further remand to the Superior Court, Forsyth County, with instructions that the Superior Court vacate the judgment for second degree murder and enter a judgment against the defendant as upon a verdict finding him guilty of involuntary manslaughter, giving him credit upon the new commitment for any time heretofore served under the judgment and commitment for second degree murder.
Reversed and remanded with instructions.