RYAN, J.

In this case we are required to decide the validity of the rule that a murder conviction may not be obtained if the victim of the homicide does not die within a year and a day after the assault.

We hold that the "year and a day" rule is part of the common law of this state; that the rule is hereby abrogated; and that the abrogation of the rule should not, and will not, be given retroactive effect.

On December 15, 1976, defendant Ross Stevenson attempted an armed robbery of the Registrar's Office of Aquinas College in Grand Rapids, Michigan. It appears that while the robbery was in progress the victim attempted to prevent the crime by jumping on the defendant from behind. A struggle ensued during which two shots were fired, one or both of which struck the victim in the abdomen. The perpetrator escaped without completing the robbery. On December 17, 1976, the defendant was arrested and charged with armed assault with intent to rob and steal, contrary to MCL 750.89; MSA 28.284, as well as assault with intent to murder, contrary to MCL 750.83; MSA 28.278.

The prosecuting attorney and the defendant subsequently entered into a plea bargain under which the charge of assault with intent to murder arising out of the shooting would be dismissed in exchange for the defendant's plea of guilty to the charge of assault with intent to rob. On February 18, 1977, the defendant was convicted upon his plea of guilty of the charge of assault with intent to rob while armed. The charge of assault with intent to murder was dismissed. Although the defendant could have been sentenced to life imprisonment, on April 15, 1977, he was sentenced instead to a prison term of not less than 6, nor more than 15, years, with appropriate credit for time already served.

Meanwhile, the shooting victim's apparent recovery from the gunshot wound proved to be illusory. On December 19, 1977, 369 days after the wound was inflicted, the victim died. An autopsy was performed in which the physician found that the cause of death was infection and hemorrhage resulting from the gunshot wound which had been inflicted over 12 months earlier.

On February 1, 1978, a complaint and warrant were issued against the defendant charging him with first-degree felony murder. On March 23, 1978, the district judge granted the defendant's motion to quash the complaint and warrant for the reason that the prosecution was barred by the common-law "year and a day" rule. The prosecutor appealed this dismissal to the circuit court and, in an order dated July 12, 1979, the circuit judge affirmed. The prosecutor appealed to the Court of Appeals, which affirmed in a published opinion. 101 Mich. App. 61; 300 N.W.2d 449 (1980). We granted leave to appeal. 410 Mich. 921 (1981). We affirm.

I

The first argument raised by the prosecutor on appeal is that the Michigan Supreme Court has never "adopted" the year and a day rule. In Chapman v People, 39 Mich. 357, 360 (1878), Chief Justice CAMPBELL wrote:

"From the earliest history of the common law, all homicides have been regarded as composed of two distinct elements, neither of which has been allowed in theory or in legal practice to merge the other. The injury which causes death is never regarded as constituting the crime of murder or manslaughter. The death of the victim not only within a year and a day, but also within the same jurisdiction was the controlling element which distinguished the guilt of the assailant from a common assault. The time and place of death were always considered as necessary to be averred, and were required to be averred as independent of the averments of assault." (Emphasis added.)

Although the prosecutor correctly characterizes this summary of the common law as obiter dictum, since the holding in Chapman was that a fatal variance existed between an indictment which alleged an assault and immediate death in Meridian Township, Ingham County, and proofs which showed a delayed death in Lansing 15 days later, his argument misses the point. In Michigan, the common law prevails except as abrogated by the Constitution, the Legislature, or this Court. Const 1963, art 3, § 7; People v Aaron, 409 Mich. 672, 722-723; 299 N.W.2d 304 (1980); People v Duffield, 387 Mich. 300, 308; 197 N.W.2d 25 (1972). The prosecutor has failed to cite any provision of the constitution, any statute, or any decision of this Court abrogating the year and a day rule, and our research satisfies us that the rule has not been abrogated in Michigan.

Unlike the doctrine of felony murder, which was of "questionable origin" (Aaron, p 689) and may have been part of the common law "only of Sir Edward Coke" (Aaron, p 695), the year and a day rule is well established within the tradition of the common law, dating back as early as 1278. In rejecting the claim that the year and a day rule applied to limit civil liability under the Indiana wrongful death act, the United States Supreme Court noted in Louisville, E St L R Co v Clarke, 152 U.S. 230, 239; 14 S Ct 579, 581; 38 L Ed 422, 424 (1894):

"In cases of murder the rule at common law undoubtedly was that no person should be adjudged `by any act whatever to kill another who does not die by it within a year and a day thereafter; in computation whereof the whole day on which the hurt was done shall be reckoned first.' 1 Hawkins, Pleas of the Crown, ch 13; 2 Hawkins, Pleas of the Crown, ch 28, § 88; 4 Blackstone, Commentaries, pp 197, 306. The reason assigned for that rule was that if the person alleged to have been murdered `die after that time, it cannot be discerned, as the law presumes, whether he died of the stroke or poison, etc., or a natural death; and in case of life, a rule of law ought to be certain.' 3 Coke, Institutes of the Laws of England, p 53."

We are satisfied that the district judge, the circuit judge, and the Court of Appeals all correctly held that under the existing common law the prosecution of this defendant was barred by the "year and a day" rule.

II

This Court has often recognized its authority, indeed its duty, to change the common law when change is required. See Aaron, supra; Placek v Sterling Heights, 405 Mich. 638; 275 N.W.2d 511 (1979); Serafin v Serafin, 401 Mich. 629; 258 N.W.2d 461 (1977); Beech Grove Investment Co v Civil Rights Comm, 380 Mich. 405; 157 N.W.2d 213 (1968); Myers v Genesee County Auditor, 375 Mich. 1; 133 N.W.2d 190 (1965). Counsel for defendant argues, however, that this Court lacks the power to change the common law so as to enlarge the scope of criminal liability and cites In the Matter of Lamphere, 61 Mich. 105; 27 N.W. 882 (1886), as authority for that claim. A careful reading of Lamphere discloses, however, that no such proposition can fairly be implied from anything written there. The Court in that case merely held that the defendant's sentence was too uncertain and indefinite as to the time of its commencement to stand. The Court then went on in obiter dicta to suggest that the Legislature should consider legislation to resolve the practical difficulties associated with consecutive sentencing. What is more important is that no limitation upon this Court's authority to "enlarge" common-law criminal liability appears in Const 1963, art 3, § 7, or can be fairly implied from its language:

"Sec. 7. The common law and the statute laws now in force, not repugnant to this constitution, shall remain in force until they expire by their own limitations, or are changed, amended or repealed."

The suggestion that crimes can only be defined by statute is not well taken, particularly in light of the fact that, in Michigan, murder is defined by the common law and not by statute. Aaron, p 713. If common-law crimes could only be contracted, not expanded, this would tend to slow needed development of the common law, since once the definition of a crime was narrowed, as in Aaron, the Court would lack the power to reverse itself and "expand" liability by readopting, for example, the felony-murder doctrine. Such a "one way" power would unduly and unnecessarily retard the development of the common law in both directions, and we therefore refuse to endorse it.

Recognizing that this Court has the authority to abolish the year and a day rule, the question remains whether the rule has outlived its usefulness and should be abolished. The original rationale for the rule was probably tied to the inability of 13th Century medicine to prove the cause of death beyond a reasonable doubt after a prolonged period of time:

"If he died after that time, it cannot be discerned, as the law presumes whether he died of the stroke or poison, etc., or a natural death; and in the case of life, the law ought to be certain." 3 Coke, Institutes of the Laws of England, p 52.

Even if expert medical testimony concerning causation had been available at that time it would not have been heard, since in the early English courts the jury reached the verdict upon their own knowledge and not upon the testimony of witnesses having personal knowledge of the facts and expert opinion testimony as is the case today. 65 Dickinson L Rev 166, 170 (1961), citing Thayer, Evidence, p 174 (1898).

The advances of modern medical science, by extending life and by providing strong evidence of the cause of death, have undermined the wisdom of the irrebuttable presumption that the death of one who expires more than a year and a day after receiving an injury was not caused by the injury. The availability of modern life-sustaining equipment and procedures, see In re Quinlan, 70 N.J. 10; 355 A.2d 647 (1976), raises the specter of the choice between terminating life-support systems or allowing the defendant to escape a murder charge. The presumption was wooden and arbitrary from the beginning, since it prevented a murder conviction even in those rare cases when causation could be proved. Now, when medical causation can be proven with much greater frequency and certainty, the old rule is simply too often demonstrably wrong to be upheld.

Of course, abolition of the rule would not relieve the prosecution of its duty to prove all of the elements of the crime, including proximate causation, beyond a reasonable doubt. A murder conviction which rests upon uncertain medical speculation as to the cause of death is not a case which has been proved beyond a reasonable doubt. Fears about murder convictions for death 5, 10, or even 20 years after the injury are therefore unfounded where proximate cause is proven beyond a reasonable doubt. If such proof is available, the conviction is justified. No repose or statute of limitations is available for murder in this state. MCL 767.24; MSA 28.964.

Recognizing that the year and a day rule is archaic and should be abandoned, we must decide whether this Court should take such action or whether deference to the Legislature is appropriate.

Counsel for defendant argues for deference to the Legislature's traditional policy of defining crimes by statute and further notes that the choice between the alternatives to the year and a day rule is complex and legislative in nature. As to the first objection, we simply note that murder is a common-law crime and the year and a day rule is a judge-made rule. Under such circumstances, courts are particularly well-suited to act; cf. Placek, supra. As to the second observation, we note that mere multiplicity of choice or a range of options does not make a decision "legislative". Further, since the Legislature remains free to change the common law, the ultimate decision as to whether to retain the rule or some form of it resides in the Legislature.

We hold, in the exercise of our constitutional authority to shape and advance the common law, that the year and a day rule has outlived its usefulness and is therefore abolished. We do so in accord with the growing trend of modern authority. Commonwealth v Ladd, 402 Pa. 164; 166 A.2d 501 (1960); State v Sandridge, 5 Ohio Op 3d 419; 365 N.E.2d 898 (1977); State v Young, 77 N.J. 245; 390 A.2d 556 (1978); Commonwealth v Lewis, 381 Mass. 411; 409 N.E.2d 771 (1980). The only court which has chosen to retain the rule since 1960 was an intermediate appellate court in Maryland. State v Brown, 21 Md. App. 91; 318 A.2d 257 (1974). In Michigan, proof of the proximate cause of death in homicide cases is hereafter to be measured by the same standard whether the victim dies before or after a year and a day; namely, proof beyond a reasonable doubt.

III

The final issue to be decided is whether our abrogation of the year and a day rule can and should be given retroactive effect so as to allow the murder prosecution in this case.

The prosecutor argues that the prohibition against ex post facto laws found in US Const, art I, § 9 and Mich Const 1963, art 1, § 10, is not implicated in this case because that bar is directed to the Legislature; that the year and a day rule is one of evidence or procedure, not substance; that the defendant had fair notice that his conduct was criminal; that the defendant did not actually rely upon the year and a day rule; and that adherence to an archaic legal fiction should not free the victim's killer. We will consider these arguments in the order presented.

It is well recognized that while the Ex Post Facto Clause does not apply directly to the judiciary, it is applicable by analogy through the Due Process Clauses of the Fifth Amendment, Marks v United States, 430 U.S. 188; 97 S Ct 990; 51 L Ed 2d 260 (1977), and the Fourteenth Amendment to the United States Constitution. Bouie v Columbia, 378 U.S. 347; 84 S Ct 1697; 12 L Ed 2d 894 (1964). This Court acknowledged the applicability of the Ex Post Facto Clause to the judiciary in its holding in People v Dempster, 396 Mich. 700, 714-718; 242 N.W.2d 381 (1976). While some courts have held that the year and a day rule is merely a rule of evidence or procedure and may therefore be abolished retroactively, we do not find that characterization controlling. One of the abuses which the colonists intended to correct with the Ex Post Facto Clause was acts which

"violated the rules of evidence (to supply a deficiency of legal proof) by admitting one witness, when the existing law required two; by receiving evidence without oath; or the oath of the wife against the husband; or other testimony which the courts of justice would not admit". Calder v Bull, 3 US (3 Dall) 386, 389; 1 L Ed 648, 649 (1798) (opinion of Chase, J.).

The key is the importance of the rights concerned and their effect on the defendant, not whether those rights can be characterized as "merely" evidentiary or procedural.

Providing fair notice that conduct is criminal is one of the central values of the Ex Post Facto Clause. Dobbert v Florida, 432 U.S. 282; 97 S Ct 2290; 53 L Ed 2d 344 (1977); Bouie v Columbia, supra. But fair notice is not the sole purpose of the clause. As the Court observed in dictum in Bouie, supra, p 353,

"An ex post facto law has been defined by this Court as one `that makes an action done before the passing of the law, and which was innocent when done, criminal; and punishes such action,' or `that aggravates a crime, or makes it greater than it was, when committed.'" (Emphasis in original.)

The following definition of an ex post facto law from Calder, supra, was adopted by reference in In re Hoffman, 382 Mich. 66, 72, fn 1; 168 N.W.2d 229 (1969):

"1st. Every law that makes an action done before the passing of the law; and which was innocent when done, criminal; and punishes such action. 2d. Every law that aggravates a crime, or makes it greater than it was, when committed. 3d. Every law that changes the punishment, and inflicts a greater punishment, than the law annexed to the crime, when committed. 4th. Every law that alters the legal rules of evidence, and receives less, or different, testimony, than the law required at the time of the commission of the offense, in order to convict the offender." Calder, p 390.

In Weaver v Graham, 450 U.S. 24, 29; 101 S Ct 960; 67 L Ed 2d 17, 23 (1981), the Court defined an ex post facto law as follows:

"In accord with these purposes, our decisions prescribe 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." (Footnotes omitted.)

Again, this is consistent with the intent of the framers of both constitutions to prohibit the abuses of the English Parliament, which had "inflicted greater punishment, than the law annexed to the offense". Calder, supra, p 389. A murderer has fair notice that his conduct is criminal, yet this Court would not approve a retroactive increase in the authorized punishment from life imprisonment to capital punishment, if that penalty were imposable. In this case, abolishing the rule retroactively would permit a possible increase in the maximum authorized punishment from life (assault with intent to rob while armed) to mandatory life without the possibility of parole (first-degree murder). Increasing the authorized penalty after the fact does not deny the defendant fair notice of what conduct is criminal, yet it still violates the rule against ex post facto criminal laws. Abrogating the year and a day rule in this case would apply this opinion to events occurring before it and would clearly disadvantage the defendant unfairly.

It is also argued that the defendant did not actually rely upon the year and a day rule at the moment he shot the victim. As dissenting Justice Pashman wrote in State v Young, 77 N.J. 245, 264-265; 390 A.2d 556 (1978), quoting Cooley, Constitutional Law, 23 U Pitt L Rev 263, 265 (1961), "The defendant in this case could not have so regulated his blows as to ensure that his victim would die a month after the year-and-a-day barrier came into existence, nor should due process afford him a right to try". Arguably, the defendant could have relied on the year and a day rule, not in expecting that the victim would survive that long, but reasonably expecting that if the victim did in fact survive that long, a murder conviction could not result. However, actual or even fictional reliance is not the sole interest protected by due process. The ex post facto principle also protects against erratic or arbitrary action improper in a lawgiver. Weaver, supra, p 29; Lewis, supra, p 775. It would be nothing if not erratic to declare for the first time today, almost five years after the year and a day rule effectively barred a murder prosecution in this case, that such a prosecution could be maintained. The defendant's subjective intent or reliance is simply not controlling in this case. Young, supra, pp 254-255. A defendant may not even be aware of various important evidentiary rules or the maximum punishment at the time of the offense, and yet such protections may not be abolished retroactively. See Calder v Bull, supra; Weaver, supra. The weight of modern authority supports the proposition that the year and a day rule cannot be abolished retroactively. Only two courts have abolished the rule with full retroactive effect; in Ladd, supra, the majority felt free to do so because the rule was said to be merely one of evidence or procedure, while in Sandridge, supra, the brief two-page opinion by the judge of the Court of Common Pleas of Cuyahoga County failed to directly address the retroactivity issue. We choose to follow the better reasoned opinions in Young, supra, and Lewis, supra, abolishing the rule purely prospectively.

The prosecutor's view that the Ex Post Facto Clause only prohibits making illegal what was legal when done is far too narrow. Under the prosecutor's analysis, the Legislature or this Court could retroactively redefine murder to include those cases in which the victim was critically injured, but fully recovered. The retroactive elimination of the requirement that the victim actually die would be justified by the rationale that the defendant did not lack fair warning that his conduct was illegal; that the defendant could not have so regulated his blows as to insure that his victim would be critically wounded but not die from the attack; and that the defendant could not have actually relied upon the victim's surviving the near-fatal attack. Since this reasoning would strip the Ex Post Facto Clause of much of its substance, we refuse to accept it. As in People v Marshall, 362 Mich. 170; 106 N.W.2d 842 (1961), our decision today is based on our interpretation of both the Michigan Constitution and the Constitution of the United States.

We feel constrained to point out that refusing to abolish the year and a day rule ex post facto does not "free" the defendant from criminal responsibility. The defendant was originally charged with assault with intent to commit murder for the attack on the victim. The fact that the victim survived for more than a year and a day was no bar to prosecution for that offense, a felony with a maximum punishment of life imprisonment. The prosecutor is barred from charging that offense now only by the plea bargain in which he agreed to request dismissal of the assault with intent to murder charge (Count II) in exchange for the defendant's plea of guilty to the charge of assault with intent to rob while armed (Count I). The plea bargain provides a separate and additional reason to forbid a murder prosecution in this case, since to do so would deprive the defendant of most if not all of the benefit of his bargain. It would violate the spirit, if not the letter, of the agreement to allow the prosecutor to obtain a guilty plea by dismissing the assault charge and then at a later date to bring a murder charge based on the very same assault.

Following the defendant's guilty plea, the trial judge sentenced the defendant to a prison term of 6 to 15 years, even though the maximum possible sentence was life imprisonment. The sentencing judge indicated his familiarity with the facts of the attempted robbery and assault, as well as his personal awareness of the seriousness of the wounds of the abdomen suffered by the victim. However, in light of a favorable presentence report and favorable letters from interested parties, including the assistant prosecutor, the circuit judge felt that the sentence imposed would best serve the interests of justice. The prosecutor is now seeking a second conviction and second sentencing in light of the subsequent death of the victim. Clearly the judge lacks authority to vacate a valid sentence and impose a heavier one in light of subsequent events. People v Barfield, 411 Mich. 700; 311 N.W.2d 724 (1981); In re Richards, 150 Mich. 421; 114 N.W. 348 (1907); People v Meservey, 76 Mich. 223; 42 N.W. 1133 (1889). We are convinced that under the facts of this particular case that same result should not be reached by the expedient of obtaining a second conviction based on the same criminal behavior.

For the foregoing reasons the judgment of the Court of Appeals affirming the quashing of the murder indictment is affirmed.

FITZGERALD, C.J., and WILLIAMS and COLEMAN, JJ., concurred with RYAN, J.