These cases present our first opportunity to construe Ohio’s wrongful imprisonment statutes, R.C. 2305.02 and 2743.48. These statutes were added to the Revised Code in 1986 by Sub. H.B. No. 609 “to authorize civil actions against the state, for specified monetary amounts, in the Court of Claims by certain wrongfully imprisoned individuals” (141 Ohio Laws, Part III, 5351), replacing the former practice of compensating wrongfully imprisoned persons by ad hoc moral claims legislation. See, generally, Comment, Wrongful Incarceration In Ohio: Should There Be More Than A Moral Obligation to Compensate? (1982), 12 Cap. U. L. Rev. 255. Under the statutory scheme, a claimant must follow a two-step process.
In the first step, the claimant must bring an action in the court of common pleas to secure a determination that he is a wrongfully imprisoned individual entitled to compensation. As relevant here, a “wrongfully imprisoned individual” was defined in former R.C. 2743.48(A) as one who satisfied four criteria:
“(1) He was charged with a violation of a section of the Revised Code by an indictment or information prior to, or on or after, the effective date of this section, and the violation charged was an aggravated felony or felony.
“(2) He was found guilty of the particular charge or a lesser-included offense * * * and the offense of which he was found guilty was an aggravated felony or felony.
“(3) He was sentenced to an indefinite or definite term of imprisonment in a state penal or reformatory institution for the offense of which he was found guilty.
“(4) Subsequent to his sentencing and during or subsequent to his imprisonment, it was determined by a court of common pleas that the offense of which he was found guilty, including all lesser-included offenses, either was not committed by him or was not committed by any person.”1
R.C. 2305.02 grants exclusive jurisdiction to the court of common pleas “to hear and determine an action or proceeding that is commenced by an *50individual * * * that seeks a determination by the court that the offense of which he was found guilty, including all lesser-included offenses, either was not committed by him or was not committed by any person.” Once the claimant secures this determination, R.C. 2743.48(D) provides that he “has and may file a civil action against the state, in the court of claims, to recover a sum of money * * *” in an amount fixed by R.C. 2743.48(E).
The issues now before this court all relate to the first stage of this process, the determination that “the offense of which * * * [the claimant] was found guilty, including all lesser-included offenses, either was not committed by him or was not committed by any person.”
I
In its first and second propositions of law, the state argues that a person acquitted by reason of self-defense is not within the definition of a “wrongfully imprisoned individual.” It bases this argument on the manner in which self-defense is treated under Ohio criminal law.
Ohio is one of only two states which retains the common-law rule on self-defense. See Martin v. Ohio (1987), 480 U.S. 228, 236. In Ohio, self-defense is an affirmative defense which the defendant is required to prove by a preponderance of the evidence. State v. Martin (1986), 21 Ohio St. 3d 91, 94, 21 OBR 386, 388, 488 N.E. 2d 166, 168, affirmed Martin v. Ohio, supra. In State v. Poole (1973), 33 Ohio St. 2d 18, 19, 62 O.O. 2d 340, 294 N.E. 2d 888, 889, we commented on the nature of affirmative defenses in the criminal law:
“As characterized by one authority, they represent not a mere denial or contradiction of evidence which the prosecution has offered as proof of an essential element of the crime charged, but, rather, they represent a substantive or independent matter ‘which the defendant claims exempts him from liability even if it is conceded that the facts claimed by the prosecution are true.’ ”
Because R.C. 2305.02 and 2743.48 require a claimant to prove that “the offense of which he was found guilty * * * was not committed by him,” (emphasis added) and not “the crime of which he was found guilty,” the state contends that the General Assembly intended to exclude persons acquitted by reason of self-defense. Citing Poole and Martin, the state argues such persons have committed an “offense,” but not a “crime.”
We disagree. In construing the Revised Code, we are required to interpret words according to the rules of grammar and common usage unless they have a particular or technical meaning. R.C. 1.42. As a matter of common usage, the words “crime” and “offense” are synonymous. See In re Jacoby (1943), 74 Ohio App. 147, 150, 29 O.O. 305, 306, 57 N.E. 2d 932, 934. For example, the words “crime” and “offense” are used interchangeably in Crim. R. 7(D), and the word “offense” is used throughout R.C. Title 29 to refer to crimes. We see nothing in the language or purpose of R.C. 2305.02 and 2743.48 which would impart to the word “offense” any technical or particular meaning different from this common usage.
The state’s fears that our holding will undermine the constitutional supports of Ohio’s self-defense rule are unfounded. This argument, too, is based on a perceived distinction between “crime” and “offense.” Our holding that a person who was acquitted by reason of self-defense is entitled to statutory compensation for wrongful imprisonment does no violence to the *51United States Supreme Court’s interpretation of the United States Constitution in Martin v. Ohio.
The state’s final contention is that compensation of persons acquitted by reason of self-defense will open the public coffers to claims by persons acquitted by reason of insanity, entrapment or other affirmative defenses. Those questions are not before us. We hold today only that a person acquitted by reason of self-defense may seek compensation for wrongful imprisonment under R.C. 2305.02 and 2743.48. We express no opinion as to the eligibility of persons acquitted by reason of other affirmative defenses.
II
Walden and Ellis, in their cross-appeals, argue that the judgments of acquittal in their new criminal trials should be given preclusive effect in the later proceedings under R.C. 2305.02. They claim that, because they had the burden of proving self-defense by a preponderance of the evidence at their criminal trials, the issue of their innocence has been litigated. The state responds that the language of R.C. 2305.02, as well as the common practice under the special moral claims bills which predated the statute, supports the view that the General Assembly intended a de novo determination of innocence as a prerequisite to recovery for wrongful imprisonment.
The doctrine of collateral estoppel, or issue preclusion, states that “if an issue of fact or law actually is litigated and determined by a valid and final judgment, such determination being essential to that judgment, the determination is conclusive in a subsequent action between the parties, whether on the same or a different claim. A party precluded under this principle from relitigating an issue with an opposing party likewise is precluded from doing so with another person unless he lacked full and fair opportunity to litigate that issue in the first action, or unless other circumstances justify according him an opportunity to relitigate that issue.” Hicks v. De La Cruz (1977), 52 Ohio St. 2d 71, 74, 6 O.O. 3d 274, 276, 369 N.E. 2d 776, 777-778; see, also, Trautwein v. Sorgenfrei (1979), 58 Ohio St. 2d 493, 12 O.O. 3d 403, 391 N.E. 2d 326.
In its opinions, the court of appeals below emphasized the qualitative differences between criminal prosecutions and civil litigation as the reason for its holdings:
“In the criminal proceeding, the burden of proof is upon the state * * *. Moreover, self-incrimination, privilege, and discovery rules are different. In the criminal proceeding, the state may not depose the defendant nor require the defendant to testify involuntarily.
“In a civil proceeding, not only is the burden of proof usually different, it being placed upon plaintiff * * * but also the rules concerning trial procedure, discovery, evidence and constitutional safeguards differ in important aspects.”
Walden and Ellis argue that, because they testified in their own defense at trial and were subject to cross-examination, the factors discussed by the court below are not “viable objections” to the application of collateral estoppel. .Therefore, they contend, the state has already had a full and fair opportunity to litigate the issue of their innocence. We do not agree.
As a general rule, a verdict or judgment of acquittal in a criminal trial is a determination that the state has not met its burden of proof on the essential elements of the crime. It is not necessarily a finding that the accused is innocent. Schrader v. *52Equitable Life Assurance Soc. (1985), 20 Ohio St. 3d 41, 46, 20 OBR 343, 347-348, 485 N.E. 2d 1031, 1035-1036; see, also, Johns v. State (1981), 67 Ohio St. 2d 325, 328, 21 O.O. 3d 204, 207, 423 N.E. 2d 863, 866; Ohio State Bar Assn. v. Weaver (1975), 41 Ohio St. 2d 97, 99-100, 70 O.O. 2d 175, 177, 322 N.E. 2d 665, 667; Friedenthal, Kane & Miller, Civil Procedure (1985) 665, Section 14.10. This is why the General Assembly intended in R.C. 2305.02 and 2743.48(A)(4) that a claimant must first affirmatively prove her innocence by a preponderance of the evidence.
Where the defendant has raised an affirmative defense, a verdict or judgment of acquittal can mean either that the defendant has proved the affirmative defense by a preponderance of the evidence or that the state has failed to prove all the elements of the crime beyond a reasonable doubt. Ellis was acquitted by a general verdict of “not guilty,” and there is no indication from the record whether it was based on self-defense or reasonable doubt. In Walden’s case, Judge Gillie’s opinion speaks both in terms of self-defense and reasonable doubt, and it is not clear on which grounds the judgment rested.
Even if we were to accept the contention that Walden, Ellis, or both, affirmatively proved self-defense at trial, there are other reasons not to apply collateral estoppel. First, this court has long recognized that the qualitative differences between civil and criminal proceedings, which were succinctly summarized by the court of appeals below, militate against giving criminal judgments preclusive effect in civil or quasi-civil litigation. Schrader, supra, at 46, 20 OBR at 347-348, 485 N.E. 2d at 1035-1036 (dictum: acquittal of accused murderer is not binding in subsequent action in probate court to determine succession to victim’s property); Johns, supra, at paragraph two of the syllabus (judgment in habeas corpus not res judicata in subsequent civil action pursuant to special moral claims bill); Weaver, supra, at 99-100, 70 O.O. 2d at 177, 322 N.E. 2d at 667 (acquittal on criminal charges not res judicata in attorney disciplinary proceeding arising out of the same transaction); see, also, Friedenthal, Kane & Miller, supra.
Second, if we were to accept the contention that collateral estoppel applies in proceedings under R.C. 2305.02, we would, in effect, be creating a preferred class of wrongful imprisonment claimants. In enacting R.C. 2305.02, the General Assembly intended that the court of common pleas actively separate those who were wrongfully imprisoned from those who have merely avoided criminal liability. We discern no purpose of the statute which would be served by a rule which would allow a person acquitted by reason of self-defense to, in effect, skip this step and go directly to the Court of Claims.
Finally, it should be noted that the state is unable to appeal a final verdict in a criminal prosecution. R.C. 2945.67(A). Because of this prohibition, the state has not had a'fair opportunity to litigate the issue of either Walden’s or Ellis’s innocence because it cannot seek correction of errors by the trial court which might have led to erroneous acquittals.
Accordingly, we hold that where a person claiming compensation for wrongful imprisonment has presented an affirmative defense of self-defense at his criminal trial, and has obtained a judgment of acquittal, that judgment is not to be given preclusive effect in a proceeding under R.C. 2305.02.
III
In its third proposition of law, the *53state contends that the claimant should be held to a “clear and convincing” standard of proof in proceedings under R.C. 2305.02. This issue was not briefed in the court below, but was apparently argued orally. We also note that the state has advanced this position in other wrongful imprisonment cases. Page v. State (Aug. 8, 1989), Franklin App. No. 89AP-222, unreported; Mueller v. State (Dec. 12, 1988), Warren App. No. CA88-05-037, unreported.
The state bases its argument on a difference in wording between R.C. 2305.02 and 2743.48. R.C. 2743.48(D) refers to a “civil action” in the Court of Claims, while R.C. 2305.02 refers only to an “action.” The state argues that the General Assembly used the words “civil action” to invoke the “preponderance” standard in R.C. 2743.48. From this, it reasons that the lack of the word “civil” before “action” in R.C. 2305.02 must indicate a different standard of proof. It also contends that a clear and convincing standard is appropriate because “the nature of the claim is essentially equitable” (citing interpretations of wrongful imprisonment statutes from other jurisdictions).
We reject the state’s argument. The General Assembly, had it wanted to do so, knew how to specify a “clear and convincing” standard. A review of the Revised Code reveals at least nineteen sections in which the General Assembly has specified a “clear and convincing” standard by using the words “clear and convincing.” See, e.g., R.C. 709.07(D) (petition to enjoin annexation); 1533.92 (appeal from denial of fishing tournament permit); 1701.59 (breach of fiduciary duty by corporate directors); 2307.80 (punitive damages in products liability actions); 3111.03 (rebuttal of presumption of paternity); 4731.22 (summary suspension of license to practice medicine); 5122.15 (civil commitment of mentally ill person). Accordingly, it is clear that the General Assembly intended to apply the usual preponderance of the evidence standard to civil proceedings under R.C. 2305.02.
Further, a claim for wrongful imprisonment is not “essentially equitable.” The action created by R.C. 2305.02 and 2743.48 is a waiver of the state’s common-law sovereign immunity, and has no parallel in the ancient dual system of law and equity.2
We therefore hold that, in a proceeding under R.C. 2305.02, the claimant bears the burden of proving his innocence by a preponderance of the evidence.
Accordingly, the judgments of the court of appeals are affirmed.
Judgments affirmed.
Moyer, C.J., Sweeney and Wright, JJ., concur. Holmes, Douglas and Resnick, JJ., concur in part and dissent in part.The wrongful imprisonment statutes were amended by Am. H.B. No. 623, effective March 17,1989, while these cases were pending. The amendments do not affect the language of those portions of the statutes at issue in the instant cases.
We express no opinion on the question of whether there is a right to a jury trial in a proceeding under R.C. 2305.02, as this question is not presented for our review.