
558 N.W.2d 245 (1996)
220 Mich. App. 47
PEOPLE of the State of Michigan, Plaintiff-Appellee,
v.
Frank Emery TICE, Defendant-Appellant.
Docket No. 181348.
Court of Appeals of Michigan.
Submitted September 4, 1996, at Grand Rapids.
Decided November 12, 1996, at 9:05 a.m.
Released for Publication February 4, 1997.
Frank J. Kelley, Attorney General, Thomas L. Casey, Solicitor General, H. Kevin Drake, Prosecuting Attorney, and William E. Molner, Assistant Attorney General, for the People.
State Appellate Defender by Deborah Winfrey Keene, for defendant-appellant on appeal.
Before DOCTOROFF, C.J., and HOOD and BANDSTRA, JJ.
DOCTOROFF, Chief Judge.
Defendant appeals as of right from his convictions of being a felon in possession of a *246 firearm, M.C.L. § 750.224f; M.S.A. § 28.421(6), and possession of marijuana, M.C.L. § 333.7403(2)(d); M.S.A. § 14.15(7403)(2)(d). Defendant was sentenced to concurrent terms of six months in jail. We reverse and remand.
In 1989, defendant was convicted, apparently by guilty plea, of attempted possession of cocaine. He was sentenced to probation, from which he was discharged in 1991. On May 4, 1994, police officers of Sherman Township conducted a search warrant at a residence used by defendant. The officers possessed a search warrant for the premises, however the affidavit in support of the warrant was not signed by its affiant. While on the premises by virtue of the warrant, the officers witnessed defendant departing the residence with a shotgun. Defendant was apparently unaware of the police presence as he left the house, and he dropped the weapon upon being ordered to do so by the police. During their search, the police noted a "stale marijuana smell" in the house and also discovered a quantity of marijuana in some dresser drawers. Defendant was subsequently arrested, tried, and convicted. He now appeals both convictions.
M.C.L. § 750.224f; M.S.A. § 28.421(6) prohibits an individual from possessing a firearm within five years of being discharged from probation. On the basis of his February 24, 1989, conviction of attempted possession of cocaine, defendant was convicted under the felon in possession statute. M.C.L. § 750.224f; M.S.A. § 28.421(6) became effective October 13, 1992. Because the statute was not yet in effect at the time of defendant's original conviction in February 1989, he contends that his conviction under the law violated the Ex Post Facto Clauses of the United States and Michigan Constitutions. A statute that affects the prosecution or disposition of criminal cases involving crimes committed before the effective date of the statute violates the Ex Post Facto Clauses if it increases the punishment for the crime. Riley v. Parole Bd, 216 Mich.App. 242, 244, 548 N.W.2d 686 (1996). Defendant contends that application of M.C.L. § 750.224f; M.S.A. § 28.421(6) served to impermissibly increase his punishment for the conviction that predated the enactment of the statute. We disagree.
In Taylor v. Secretary of State, 216 Mich. App. 333, 548 N.W.2d 710 (1996), this Court rejected a similar ex post facto argument. The petitioner complained of legislation that, on the basis of his previous driving record, prevented him from obtaining a license to drive certain industrial vehicles. The prohibitive legislation became effective after the petitioner had already incurred the previous driving infractions, thus petitioner claimed the law imposed ex post facto punishment for the earlier infractions. This Court stated:
While this may appear, from petitioner's perspective, to be additional punishment for past driving infractions, it is actually an exercise of the state's power to enhance safety, and the concomitant life, health, and welfare of the public, in the use of the state's road system. This case, accordingly, comes within the ambit of Hawker v. New York, 170 U.S. 189; 18 S.Ct. 573; 42 L.Ed. 1002 (1898).
In Hawker, the plaintiff had been convicted of a felony and sentenced to prison. After he served his sentence and was released, he sought to become a licensed physician. However, after his incarceration, the State of New York had passed a law absolutely prohibiting former felons from being licensed to practice medicine. The United States Supreme Court found that, because the state's predominant interest was in prescribing qualifications for admission to the practice of medicine, there was no violation of the Ex Post Facto Clause. [Id. at 340, 548 N.W.2d 710.]
The Taylor Court went on to find that "the legislation in issue, directed to considerations of health and safety and having only incidental punitive aspect, does not violate the prohibition against ex post facto laws." Id. at 342, 548 N.W.2d 710.
In this case, the statute M.C.L. § 750.224f; M.S.A. § 28.421(6) is obviously punitive in that it imposes criminal penalties for its violation. This does not, however, establish that the statute impermissibly punished defendant for acts that preceded the date the statute took effect. To the contrary, the *247 conduct being punished in this case was defendant's possession of a firearm at a time after the enactment of the statute. While tied to defendant's status as a convicted felon, the punishment was not imposed for the prior crime, but for his recent act of possessing a firearm. Furthermore, the state's predominant interest in enacting M.C.L. § 750.224f; M.S.A. § 28.421(6) was not the infliction of further punishment on those who had been convicted of previous felonies. Instead, the primary purpose of the statute was to protect the public by precluding certain convicted felons from possessing firearms. Because the protection of public safety is a valid exercise of the police power, Taylor, supra, we find that application of M.C.L. § 750.224f; M.S.A. § 28.421(6) to a person who is a convicted felon as a result of a conviction of a felony committed before the date that statute took effect does not violate the Ex Post Facto Clauses of the United States and Michigan Constitutions.
Defendant next contends that he was denied his right to be free from unreasonable searches and seizures where police searched his residence pursuant to a warrant that was based on an unsigned affidavit. We find that this case should be remanded for a determination concerning whether the facts set forth in the unsigned affidavit were also made under oath to a magistrate.
A search warrant that lacks an affiant's signature is presumed to be invalid, but the presumption can be rebutted by a showing that the facts in the affidavit were presented under oath to the magistrate who authorized the warrant. People v. Mitchell, 428 Mich. 364, 365-366, 408 N.W.2d 798 (1987). In this case, the affidavit for a search warrant contained a space where the magistrate was to put his signature, however the space was blank. Pursuant to Mitchell, the critical question is whether the affidavit was made "on oath to a magistrate." Id. at 368-369, 408 N.W.2d 798. Mitchell indicates that it would suffice if the information in the affidavit was sworn to before a magistrate. Id. Thus, though the affidavit was unsigned, it could still be valid if the prosecution could show that the factual allegations offered in support of the affidavit were made by the affiant under oath to the magistrate. Id. at 369, 408 N.W.2d 798.
In this case, there is no evidence on the record regarding the circumstances under which the affidavit supporting the search warrant was presented to the magistrate. Had the issue been raised below, the prosecution might have been able to offer evidence showing that the affiant also presented the facts set forth in the affidavit under oath to the magistrate. As the record stands before us on appeal, however, we are unable to determine the circumstances under which the affiant presented the facts on which the warrant was based. Accordingly, we remand to the trial court for a determination whether the facts set forth in the affidavit were also presented to the magistrate under some form of oath or affirmation. If the trial court finds on remand that the facts set forth in the affidavit were so presented, defendant's convictions should not be disturbed on the basis of this issue. However, if the trial court finds that the facts set forth in the affidavit were not so presented, then suppression of the evidence obtained pursuant to the warrant is the proper remedy. People v. Chambers, 195 Mich.App. 118, 120, 489 N.W.2d 168 (1992).
Finally, defendant contends that the trial court erred in instructing the jury that defendant was a convicted felon. Defendant argues that this invaded the jury's province by establishing an element of the crime of being a felon in possession of a firearm, M.C.L. § 750.224f; M.S.A. § 28.421(6). We agree and reverse.
M.C.L. § 750.224f(2); M.S.A. § 28.421(6)(2) makes it clear that an element of the crime is a defendant's status as a convicted felon. The statute provides in pertinent part:
A person convicted of a specified felony shall not possess, use, transport, sell, purchase, carry, ship, receive, or distribute a firearm in this state until all of the following circumstances exist. [Emphasis added.]
On the record, but outside the presence of the jury, defendant told the trial judge that he had been convicted of "a two-year high *248 court misdemeanor," but not a felony. Defendant thus contended that he should not be considered a convicted felon for purposes of M.C.L. § 750.224f; M.S.A. § 28.421(6). The trial court responded to defendant's argument as follows:
Mr. Tice, under the law in which you're charged, the Court is charged with making a determination whether it's a three-year or a five-year probationary period depending on the definition of the crimes in which you have been convicted of [sic]. The court has read that over and made the determination that you are a convicted felon. In the context of that law the probationary period is five years. [Emphasis added.]
Thereafter, the trial court instructed the jury as follows:
The second question is, was Mr. Tice a convicted felon? Within the context of the crime in which he stands here charged, he was a convicted felon. [Emphasis added.]
As noted above, whether defendant was a convicted felon was an element of the crime of being a felon in possession of a firearm. When a trial court instructs that an essential element of a criminal offense exists as a matter of law, error requiring reversal will be found. People v. Allensworth, 401 Mich. 67, 70-71, 257 N.W.2d 81 (1977), quoting People v. Reed, 393 Mich. 342, 349, 224 N.W.2d 867 (1975); see also People v. Gaydosh, 203 Mich.App. 235, 238, 512 N.W.2d 65 (1994). Because the jury was not allowed to consider defendant's argument that he was convicted of a misdemeanor as opposed to a felony, the trial court impermissibly undermined the essential fact-finding function of the jury and freed the prosecution from its duty to prove each element of the crime charged beyond a reasonable doubt. Accordingly, defendant's conviction of being a felon in possession of a firearm is reversed, and the case is remanded for a new trial on that charge.
Reversed and remanded. On remand, the trial court is instructed to determine whether the facts set forth in the unsigned affidavit in support of the warrant were also presented to the magistrate under some form of oath or affirmation. In addition, the trial court is to conduct a new trial with respect to the charge of being a felon in possession of a firearm.
