¶ 1. The issue before the courtis whether Wis. Stat. § 948.05 prohibiting the sexual exploitation of a child violates the First and Fourteenth Amendments to the United States Constitution and Article I, § 3 of the Wisconsin Constitution for failing to require that the State prove that a distributor of sexually explicit materials had knowl*121edge of the minority of the person(s) depicted in the materials. We hold that the statute does violate the federal and state constitutions as it applies to distributors of such materials, and decline to save the statute insofar as it applies to those accused of the proscribed activities of § 948.05(l)(c) which do not entail a personal meeting between the minor depicted and the accused.
H
¶ 2. The defendant was charged with, among other felonies, two counts of sexual exploitation of a child contrary to Wis. Stat. § 948.05(l)(c) (1995-96)1 for his reproduction and/or distribution of photographs, electronically stored images, and other pictorial reproductions of a child engaging in sexually explicit conduct. Section 948.05 states in relevant part as follows:
(1) Whoever does any of the following with knowledge of the character and content of the sexually explicit conduct involving the child is guilty of a class C felony.
(c) Produces, performs in, profits from, promotes, imports into the state, reproduces, advertises, sells, distributes or possesses with intent to sell or distribute, any undeveloped film, photographic negative, photograph, motion picture, videotape, sound recording or other reproduction of a child engaging in sexually explicit conduct.
*122(3) It is an affirmative defense to prosecution for a violation of this section if the defendant had reasonable cause to believe that the child had attained the age of 18 years, and the child exhibited to the defendant, or the defendant's agent or client, a draft card, driver's license, birth certificate or other official or apparently official document purporting to establish that the child had attained the age of 18 years. A defendant who raises this affirmative defense has the burden of proving this defense by a preponderance of the evidence.
(Emphasis added.)
¶ 3. The defendant moved to dismiss the sexual exploitation charges on several grounds, including, as is relevant here, that Wis. Stat. § 948.05 is unconstitutional because it does not require that the State prove that the defendant had knowledge of the minority of the person(s) depicted in the sexually explicit materials, but instead impermissibly allocates to the defendant the burden to prove lack of such knowledge by a preponderance of the evidence as an affirmative defense. The circuit court agreed with the defendant, and basing its decision on United States v. X-Citement Video, Inc., 513 U.S. 64 (1994), ruled that § 948.05 was unconstitutional in its entirety and dismissed the two charges.
¶ 4. The State appealed arid the court of appeals reversed. State v. Zarnke, 215 Wis. 2d 71, 572 N.W.2d 491 (Ct. App. 1997). On appeal, the defendant conceded that the decision of the circuit court for Eau Claire County, Honorable Benjamin D. Proctor, holding the entirety of Wis. Stat. § 948.05 unconstitutional, was in error as to those portions of the statute which regulate the production of sexually explicit materials involving minors and which, presumably, involve personal inter*123action between the child-victim and the accused. However, the defendant maintained that the portion of § 948.05(l)(c) addressing the distribution of sexually explicit materials involving minors, and which did not involve the personal interaction between the child-victim and the accused, was unconstitutional.
¶ 5. The State agreed with the defendant that the statute was constitutional as applied to the production, but unconstitutional as applied to the distribution, of sexually explicit materials involving children. The State presented the issue for review as one centered upon the extent to which the statute could be saved to avoid dismissal of the charges against the defendant.
¶ 6. The court of appeals agreed with both parties that when an accused did not have the opportunity to personally meet the child-victim, the State must carry the burden to prove, as an element of the offense under Wis. Stat. § 948.05, that a defendant distributor had knowledge of the minority of the child-victim depicted in the sexually explicit material in issue. It based this conclusion on X-Citement Video. However, the court wrote that § 948.05 did in fact place that necessary burden upon the State, and, therefore, was not unconstitutional. The court provided further that in the alternative, the statute could be saved by first severing the offending portions and then reading into those same offending portions the requirement that the State prove all the elements of the offense, which would include proof of the defendant's knowledge of the minority of the child-victim.
¶ 7. The defendant appealed and we granted his petition for review. We now reverse the court of appeals' decision. We hold that Wis. Stat. § 948.05 on its face does not set forth the requirement that the *124State carry the burden to prove that the defendant had knowledge of the minority of the child-victim depicted in the sexually explicit materials for which the prosecution is being brought. Therefore, the statute as written is unconstitutional as it applies to the distribution of sexually explicit material depicting minors, as well as to the other prohibited conduct which does not entail a personal interaction between the accused and the child-victim.
II.
¶ 8. The constitutionality of a statute is a question of law that we review de novo. State v. Post, 197 Wis. 2d 279, 301, 541 N.W.2d 115 (1995). Ordinarily, there is a presumption of constitutionality for a legislative enactment. Id. In most circumstances, those challenging the constitutionality of a statute have the burden to prove that the statute is unconstitutional beyond a reasonable doubt. Norquist v. Zeuske, 211 Wis. 2d 241, 250, 564 N.W.2d 748 (1997). However, because Wis. Stat. § 948.05 implicates First Amendment rights,2 the State has the burden of proving *125beyond a reasonable doubt that the-statute is constitutional. State v. Thiel, 183 Wis. 2d 505, 523, 515 N.W.2d 847 (1994); City of Madison v. Baumann, 162 Wis. 2d 660, 668-69, 470 N.W.2d 296 (1991).
¶ 9. The State does not argue that the statute is constitutional as it applies to distributors of sexually explicit materials involving children, but rather concedes that it is unconstitutional and argues for saving it. Regardless, we believe that the statute's constitutional infirmities merit our discussion.
A
¶ 10. Both parties to this appeal agree that the statute places the burden as to the question of the defendant's knowledge of the minority of one or more of the persons depicted in the sexually explicit materials upon the defendant as an affirmative defense. However, the court of appeals independently concluded that for distributors of sexually explicit materials, the burden to prove this knowledge was placed on the State.
¶ 11. The court of appeals held that the legislature did not intend the affirmative defense set forth in Wis. Stat. § 948.05(3) to apply to the violations of Wis. Stat. § 948.05(l)(c) that do not involve a face-to-face involvement with the child-victim. In so holding, the court began with the premise that the legislature has always intended to prevent conviction under § 948.05, and its predecessor in Wis. Stat. § 940.203 (1987-88) (repealed effective July 1, 1989), of one who was reasonably ignorant of the minority of persons depicted in sexually explicit material.
*126¶ 12. The court believed that when, in 1987, Wis. Stat. § 940.203 was renumbered as Wis. Stat. § 948.05 and amended by the legislature to shift the burden of proof of knowledge from the State to the defendant, the legislature did not change its underlying policy that those free of guilty knowledge could not be punished for sexual exploitation of a child. Zarnke, 215 Wis. 2d at 78. Because the legislature knew that guilty knowledge had been, and continued to be, an element of the offense, the court of appeals believed that the legislature could not have intended the affirmative defense to apply to the instant case because to do so would be unreasonable and absurd — where the defendant did not have a face-to-face involvement with the victim, it would be impossible for the defendant to satisfy the defense. The court agreed with the defendant that one who is not involved in face-to-face exploitation could never satisfy the requirement under the affirmative defense that the child produced suitable documentary evidence of his or her majority. Construing the statute to avoid an unreasonable or absurd result, Schwartz v. DILHR, 72 Wis. 2d 217, 222, 240 N.W.2d 173 (1976), the court concluded that the affirmative defense could apply only to those categories of criminal activity in which it is reasonable to conclude that the defendant could have had the opportunity to meet the child-victim face-to-face.
¶ 13. While we agree with the court of appeals that the affirmative defense set out in Wis. Stat. § 948.05(3) is a practical impossibility for distributors of sexually explicit materials, we decline to follow its reasoning and agree instead with both parties that as currently written, the statute does provide the defendant with an affirmative defense as to all the crimes chargeable in this statute.
*127¶ 14. The statute unambiguously places the burden of proving lack of knowledge on the defendant in the affirmative defense provided by Wis. Stat. § 948.05(3). Subsection (3) neither explicitly, nor implicitly, places the burden of proof of the defendant's knowledge upon the State. To the contrary, the statute clearly burdens the defendant with proving his or her reasonable cause to believe that the person depicted had reached the age of majority. Any other reading, no matter how tempting, ignores the plain language of the statute. Therefore, we find that the statute on its face does not allocate to the State the burden to prove that the defendant had knowledge of the minority of the child-victim. Because the statute is clear on its face, without any ambiguity, statutory construction is not appropriate in the first instance. State v. Chrysler Outboard Corp., 219 Wis. 2d 130, 167, 580 N.W.2d 203 (1998).
B
¶ 15. Our finding does not resolve the more fundamental question, assumed by the parties and the courts below but not discussed: that is, whether as a constitutional matter, the legislature may define a statute in which the defendant's knowledge of minority is not an element of the offense as it has done so here.3 We hold that it may not.
*128¶ 16. It is well-established that "the Dué Process Clause protects the accused against conviction except upon proof beyond a reasonable doubt of every fact necessary to constitute the crime with which he is charged." In re Winship, 397 U.S. 358, 364 (1970). It is equally true that the State may offer a defendant an affirmative defense to a crime charged, and place upon that defendant the burden to prove that defense, so long as the defense does not in fact work to negate one of the elements of the crime charged. See Patterson v. New York, 432 U.S. 197 (1977); Martin v. Ohio, 480 U.S. 228 (1987).
¶ 17. Prior to 1987, the provisions of Wis. Stat. § 948.05 were embodied in Wis. Stat. § 940.203 (1985-86). Under the earlier section, the State was burdened with proving that a defendant had knowledge of the minority of those involved in the pornography. See Wis. Stat. § 940.203 (1985-86). In 1987, the legislature passed 1987 Wis. Act 332, which among other actions involving crimes against children generally, renumbered § 940.203 to the current § 948.05 and amended its language to shift the burden of proof as to the knowledge of the minority of the child-victim from the State to the defendant. See Legislative Council Note, 1987 Wis. Act 332, Wis. Stat. Ann. § 948.05 (West 1996).
*129¶ 18. While legislatures are presumed to pass constitutional statutes, Post, 197 Wis. 2d at 301, there are "constitutional limits beyond which the States may not go" in reallocating "burdens of proof by labeling as affirmative defenses at least some elements of the crimes" that have been defined in their statutes. Patterson, 432 U.S. 197, 210. In this regard, the Court in Patterson noted the following:
"[I]t is not within the province of a legislature to declare an individual guilty or presumptively guilty of a crime." McFarland v. American Sugar Rfg. Co., 241 U.S. 79, 86 (1916). The legislature cannot "validly command that the finding of an indictment, or mere proof of the identity of the accused, should create a presumption of the existence of all the facts essential to guilt." Tot v. United States, 319 U.S. 463, 469 (1943). See also Speiser v. Randall, 357 U.S., at 523-525. Morrison v. California, 291 U.S. 82 (1934), also makes the point with sufficient clarity.
Id. With Wis. Stat. § 948.05, the legislature has indeed unconstitutionally allocated to the defendant a burden which must be placed upon the State.
¶ 19. The United States Supreme Court has held that a State may impose strict or absolute criminal liability by defining criminal offenses without any element of scienter. Smith v. California, 361 U.S. 147, 150 (1959). However, the State is limited in its use of strict liability statutes, particularly so in the area of expression where "an elimination [of the scienter requirement] may tend to work a substantial restriction on the freedom of speech and of the press." Id. Further, while some legal doctrines are usually consistent with the Constitution, at times they "cannot be *130applied in settings where they have the collateral effect of inhibiting the freedom of expression, by making the individual the more reluctant to exercise it." Id. at 151. Strict liability is one such doctrine. Id. at 150-51; see also Mishkin v. New York, 383 U.S. 502, 510 (1965) ("The Constitution requires proof of scienter to avoid the hazard of self-censorship of constitutionally protected material and to compensate for the ambiguities inherent in the definition of obscenity."); Hustler Magazine v. Falwell, 485 U.S. 46, 52 (1987) ("[A] rule that would impose strict liability on a publisher for false factual assertions would have an undoubted 'chilling' effect on speech. . .that does have constitutional value.") The same is true of laws regulating the sexual exploitation of children. New York v. Ferber, 458 U.S. 747, 765 (1982). "[CJriminal responsibility may not be imposed [upon those involved with nonobscene, sexually explicit materials depicting minors] without some element of scienter on the part of the defendant." Id.
¶ 20. The Court in Smith explained the constitutional problems associated with strict liability offenses in the area of speech:
The appellee and the court below analogize this strict liability penal ordinance to familiar forms of penal statutes which dispense with any element of knowledge on the part of the person charged, food and drug legislation being a principal example. We find the analogy instructive in our examination of the question before us. The usual rationale for such statutes is that the public interest in the purity of its food is so great as to warrant the imposition of the highest standard of care on distributors — in fact an absolute standard which will not hear the distributor's plea as to the amount of care he has used. *131[citations omitted] His ignorance of the character of the food is irrelevant. There is no specific constitutional inhibition against making the distributors of food the strictest censors of their merchandise, but the constitutional guarantees of the freedom of speech and of the press stand in the way of imposing a similar requirement on the bookseller.
Smith, 361 U.S. at 152-53; See also State v. Collova, 79 Wis. 2d 473, 484-85, 255 N.W.2d 581 (1977)(strict liability statutes have been applied in Wisconsin in " 'regulatory criminal statutes'" where "[t]he persons to whom the regulations are directed are generally in a position to exercise [a] high degree of care.").
¶ 21. With its decision in X-Citement Video, the Supreme Court suggested strongly that some level of scienter as to the minority of the child-victim was constitutionally required where there was no reasonable expectation of a face-to-face meeting between an accused and the minor. It wrote that age of minority possessed the status of an elemental fact because "non-obscene, sexually explicit materials involving persons over the age of 17 are protected by the First Amendment." X-Citement Video, 513 U.S. at 72 (citations omitted). "[0]ne would reasonably expect to be free from regulation when trafficking in sexually explicit, though not obscene, materials involving adults. Therefore, the age of the performers is the crucial element separating legal innocence from wrongful conduct." Id. at 73. We agree that the age of the performer is an elemental fact, and based upon the Court's decision in Smith, find that the government must prove some level of scienter as to the performer's minority. Therefore, to escape our finding that the statute is unconstitutional, a defendant who is in no position to garner the age of *132the minor may not be held strictly liable where the individual depicted is in fact a minor.
¶ 22. Wisconsin Stat. § 948.05 is not a strict liability statute, for it is possible for a defendant to escape liability under § 948.05 by proving a lack of knowledge. Strictly speaking, a strict liability offense is one which affords an individual no opportunity to prove a lack of knowledge. However, the current § 948.05, as it applies to distributors, is indistinguishable from a strict liability statute, since it is virtually impossible for a defendant as a distributor to meet his or her burden.
¶ 23. A distributor of pornography may be one step, or many steps, removed from its production, and the further removed the more difficult — the closer to impossible — it is for the distributor to garner the identification required of Wis. Stat. § 948.05(3). We agree with the Supreme Court's observation that "[t]he opportunity for reasonable mistake as to age increases significantly once the victim is reduced to a visual depiction, unavailable for questioning by the distributor or receiver." X-Citement Video, 513 U.S. at 72 n.2. Here, a defendant who is a distributor is never in the position to have the child-victim exhibit to him or her an "official document" that is required of the affirmative defense. We find that this affirmative defense which could never be proved by most of the actors in § 948.05(l)(c) essentially reduces the statute to one which is in effect strict liability. Therefore, we hold that the statute is unconstitutional as it applies to those activities which do not include some interaction between the accused and the child-victim.
¶ 24. While we find that the affirmative defense as provided in Wis. Stat. § 948.05 does not provide the constitutionally required element of scienter, we stop *133short of addressing the level of scienter that would withstand scrutiny.
¶ 25. We hold that an essential element of the crime specified in Wis. Stat. § 948.05 must be an accused's knowledge of the minority of the child-victim, that the State must bear the burden of proving some level of scienter as to that essential element where an accused's conduct does not entail a personal meeting with the minor, and that as currently drafted, the legislature has not constitutionally allocated that necessary burden.
f-H HH HH
¶ 26. "Although this court will strive to construe legislation so as to save it against constitutional attack, it must not and will not carry this to the point of perverting the purpose of a statute." State v. Hall, 207 Wis. 2d 54, 82, 557 N.W.2d 778 (1997).
¶ 27. The State would have us save Wis. Stat. § 948.05 for application against the defendant by severing the offending portions and then saving those same portions by imposing on them the required State burden. Specifically, the State suggests that we sever the following emphasized language from § 948.05(l)(c):
"Produces, performs in, profits from, promotes, imports into the state, reproduces, advertises, sells, distributes, or possesses with intent to sell or distribute, any undeveloped film, photographic negative, photograph, motion picture, videotape, sound recording or other reproduction of a child engaging in sexually explicit conduct."
(Emphasis supplied.) We understand the parties' objections to the emphasized language arising from their *134recognition that none of these activities will generally entail a face-to-face meeting between the accused and the child-victim.
¶ 28. Severance of the offending language of the statute requires a rule of construction specifically authorized by Wis. Stat. § 990.001(11):
The provisions of the statutes are severable. The provisions of any session law are severable. If any provision of the statutes or of a session law is invalid, or if the application of either to any person or circumstance is invalid, such invalidity shall not affect other provisions or applications which can be given effect without the invalid provision or application.
¶ 29. We recognize that we have the authority to sever the above-emphasized language as the State asks. However, the State does not ask us to sever this language to save the remaining provisions. Instead, it makes the unusual request that we sever the language to save the statute as it applies to those same severed provisions. To do this, the State asks that we reinsert into the statute this severed language, first imposing upon that language an appropriate element of scienter. In the State's view, by so acting we would read into the statute a constitutional requirement that is not now explicitly present.
¶ 30. In X-Citement Video, the Supreme Court supported its construction of a federal statute, 18 U.S.C. § 2822, to require that the government prove the defendant's knowledge of the minority of the person(s) depicted in sexually explicit materials with its "cases interpreting criminal statutes to include broadly applicable scienter requirements, even where the statute by its terms does not contain them." X-Citement *135Video, 513 U.S. at 70. This court has similarly supplied statutory deficiencies by court rule in order to save a statute. See State ex rel. Chobot v. Circuit Court, 61 Wis. 2d 354, 212 N.W.2d 690 (1973) (saving a deficient statute regulating obscenity by judicially defining the term "obscene"); State v. Post, 197 Wis. 2d 279, 541 N.W.2d 115 (1995) (saving a deficient statute to construe it to include the right to request a jury for discharge hearings under Wis. Stat. §§ 980.09 and 980.10).
¶ 31. While when necessary, we have at times severed portions of a statute's language, and at other times have read into a deficient statute a constitutional requirement, the State's request that we save all of Wis. Stat. § 948.05 would require this court to combine two distinct saving doctrines, which we are not inclined to do under the circumstances of this case. During oral arguments the State suggested that this court did combine these two saving measures in City of Madison v. Nickel, 66 Wis. 2d 71, 223 N.W.2d 865 (1974) and should do so again here. We will not extend our actions in Nickel to this case.
¶ 32. In Nickel, this court was called upon to determine the constitutionality of a Madison city ordinance proscribing obscenity. As enacted, the ordinance defined obscenity in accord with the then-current constitutional standards, a point which this court considered to be "an obvious attempt by the Madison Common Council to create an obscenity ordinance consonant with the then-controlling judicial definition of obscenity within constitutional limits." Id. at 80. When the constitutional standards were subsequently redefined by Miller v. California, 413 U.S. 15 (1973), the ordinance was called into question.
*136¶ 33. In saving the ordinance, this court severed the portion of the ordinance that, following Miller, provided an unconstitutional definition of obscenity. Id. at 80. We then supplemented the ordinance using the court's "authoritative judicial construction" and held that the now undefined term "obscene" encompassed the court's definition of the term "obscene" in Chobot. Id. at 80-81.
¶ 34. Nickel is distinguishable from the instant case. When the Supreme Court repudiated the definition of obscenity that had been constitutional prior to Miller, the Court stated that regulation of depictions of sexual conduct needed to specifically define the conduct through "applicable state law, as written or authoritatively construed." Nickel, 66 Wis. 2d at 75 (quoting Miller, 413 U.S. at 24).
¶ 35. Following Miller, this court in Chobot confronted Wisconsin's obscenity statute and found that it was deficient under Miller only in that it did not contain an express definition of obscenity as required by that case. Chobot, 61 Wis. 2d at 366. In facing the question of whether this court could "save the section by interpretation and supply a constitutional definition of obscenity," id., we found that we had the power to do so, relying upon precedent supporting the supplementation of deficiencies to save a statute, id. at 367, and upon the Miller Court's proposition that a state court could "authoritatively construe" the statute.
¶ 36. Nickel presented a more difficult problem than did Chobot, for unlike the state statute in Chobot which contained no obscenity definition, the ordinance in Nickel did define obscenity, albeit in a manner no longer consistent with the constitution. As noted, this court removed the unconstitutional definition, thereby leaving the ordinance without a definition. It then *137relied on Chobot as support for its authority to supply the now-deficient ordinance with a definition that fell within the boundaries of the constitution.
¶ 37. The instant case differs in two significant ways from this court's actions in Nickel. First, severing the offending language will not leave the statute constitutionally deficient as was the case in Nickel. Following severance, we will not need to fill a deficiency in order to save the remainder of the statute.
¶ 38. Second, the decision in Chobot, from which Nickel finds its authority, was subsequently called into question. State v. Princess Cinema of Milwaukee, 96 Wis. 2d 646, 292 N.W.2d 807 (1980). In Princess Cinema, we found that the same state statute considered and saved in Chobot was now unconstitutionally over-broad, albeit based upon a question not reached in the earlier case. Recognizing first that we had the authority to rectify the continuing constitutional infirmities, we declined, "[a]s a matter of policy.. .to further act to rectify the deficiencies in [the] statute[, for the] problems of public policy and the regulation of criminal conduct are for the legislature." Id. at 661. This court emphasized that we were "not simply 'giving up' on the establishment of a constitutionally permissible scheme for regulating obscenity. We [were] recognizing that our job is one of interpreting statutes, not redrafting them." Id. at 662.
¶ 39. Given that in the Nickel decision we satisfied a deficiency in a statute that resulted from a severance, where no such deficiency will follow our severance here, and that Nickel itself was based upon a case which we later refused to make aright by the same authority which the State now urges us to invoke, we believe that that case does not control our actions here.
*138¶ 40. Nor do we believe that X-Citement Video controls. In X-Citement Video, the Court supported its interpretation that a federal statute did require proof as to the defendant's knowledge of the minority of a performer with what it found to be legislative silence on the matter. That is, the Court would "presume a scienter requirement in the absence of express contrary intent." Id. at 71-72.
¶ 41. Quite the contrary is true here, as the language of Wis. Stat. § 948.05 is not silent on the scienter requirement, as it explicitly allocates the burden regarding knowledge to the defendant. In addition, legislative history explicitly demonstrates a legislative intent to burden the defendant with proof of his or her lack of knowledge. See Legislative Council Note, 1987 Wis. Act 332, Wis. Stat. Ann. § 948.05 (West 1996). To read into the statute the requirement that the State bear the burden to prove the defendant's knowledge of minority would be contrary to the legislature's explicit intentions.
¶ 42. At oral argument, the State suggested that the legislature's explicit intent as evinced by legislative history is not what appears to be most clear from a reading of that history. Instead, the State suggests that we should consider the legislature's implicit intent, which it believes was really an intent to enact legislation that would allow it to legislate to the limits of the constitution. As its argument goes, when Wis. Stat. § 948.05 was passed in 1987, the Supreme Court's decision in Ferber was the last word on the constitutionality of statutes governing sexual exploitation of children, and that the legislature believed in good faith that Ferber permitted placing upon the defendant the burden to prove lack of knowledge of the minority of a person depicted in sexually explicit materials. Because *139the legislature enacted a statute that was constitutional then, we should assume that the legislature would intend to place the burden of the defendant's knowledge on the State when that burden is constitutionally required.
¶ 43. We might agree with the State that the legislature's implicit intent was to draft a statute that went to the limits of the constitution. However, that the legislature intends to pass statutes which are constitutional is always our starting point in such an inquiry as this. See State v. Janssen, 219 Wis. 2d 362, 580 N.W.2d 260 (1998)(ordinarily, a statute is presumed to be constitutional). But were we to rewrite a statute whenever it failed constitutional muster in order to save it, using any means possible, the legislature would soon realize that it need not be concerned with constitutional limitations: the judiciary could always be relied upon to mend and mold its language to fit within constitutional constraints.
¶ 44. "While a statute should be held valid whenever by any fair interpretation it may be construed to serve a constitutional purpose, courts cannot go beyond the province of legitimate construction to save it, and where the meaning is plain, words cannot be read into it or out of it for the purpose of saving one or other possible alternative." Hall, 207 Wis. 2d at 82 (citations omitted). It is well-established that "[w]here the language used in a statute is plain, the court cannot read words into it that are not found. . .even to save its constitutionality, because this would be legislation and not construction." Mellen Lumber v. Industrial Comm., 154 Wis. 114, 120, 142 N.W. 187 (1913), citing Rogers-Ruger Co. v. Murray, 115 Wis. 267, 91 N.W. 657 (1902).
*140¶ 45. Finally, " '[although this Court will often strain to construe legislation so as to save it against constitutional attack, it must not and will not carry this to the point of. . judicially rewriting it". X-Citement Video, 513 U.S. at 86 (Scalia, J., dissenting) (quoting Commodity Futures Trading Com'n v. Schor, 478 U.S. 833, 841 (1986)). "Otherwise, there would be no such thing as an unconstitutional statute." X-Citement Video, 513 U.S. at 86 (Scalia, J., dissenting).
¶ 46. In view of the above discussion, we believe that severing the offending portions of the statute, and then reading into those same portions a burden that the legislature explicitly rejected, would be an act of legislation. The legislature can draft a permissible and constitutionally valid statute. It has shown that it has the ability to do so in drafting former Wis. Stat. § 940.203 (1985-86) and in drafting current Wis. Stat. § 948.12. In § 948.12, for .instance, the legislature did enact, as an element to be proven by the State, the requirement that the defendant knew or should have known the minority of the child-victim depicted in the material at issue. The legislature could have done so here as well, if it so intended. To this extent, it is the legislature's job, not this court's, to amend the invalid portion of Wis. Stat. § 948.05(l)(c) to conform to the constitutional dictates of the First Amendment of the United States Constitution and Article I, § 3 of the Wisconsin Constitution.
¶ 47. The severed portion of Wis. Stat. § 948.05(l)(c) cannot be saved. Accordingly, the two counts against the defendant Zarnke which are based on his distribution of sexually explicit materials involving a minor are to be dismissed, for § 948.05(l)(c) *141cannot be applied in a constitutional manner to the defendant.
¶ 48. With the removal of the offending language, § 948.05(l)(c) now reads:
Produces or performs in any undeveloped film, photographic negative, photograph, motion picture, videotape, sound recording or other reproduction of a child engaging in sexually explicit conduct.
We explicitly reserve the question of whether this remaining portion of § 948.05(l)(c) is constitutional.
By the Court.-The decision of the court of appeals is reversed and the cause is remanded to the circuit court for further proceedings consistent with this opinion.
All references are to the 1995-96 version of the statutes unless otherwise indicated.
"[T]he Fourteenth Amendment requires that regulation by the States of obscenity conform to procedures that will ensure against the curtailment of constitutionally protected expression, which is often separated from obscenity only by a dim and uncertain line." Bantam Books, Inc. v. Sullivan, 372 U.S. 58, 66 (1963). Here we are not considering an obscenity statute, but an analogous demarcation between protected and unprotected speech is involved. The First Amendment is implicated in this question because the "age of the performers is the crucial element separating legal innocence from wrongful conduct." United States v. X-Citement Video, Inc., 513 U.S. 64, 73. "[Nlonobscene, sexually explicit materials involving persons *125over the age of 17 are protected by the First Amendment," Id. at 72, while nonobscene, sexually explicit materials involving persons under the age of 18 are not.
The legislature explicitly removed knowledge as an element of the offense and provided the defendant with an opportunity to prove lack of knowledge as an affirmative defense. See Legislative Council Note, 1987 Wis. Act 332, Wis. Stat. Ann. § 948.05 (West 1996). Therefore, lack of knowledge is not now an element of the offense. "There is a clear distinction [ ] between the elements of [an] offense and the elements of an *128affirmative defense." United States v. Falkowski, 900 F. Supp. 1207, 1214 (D. Alaska 1995) (citation omitted). The defendant in the instant case must disprove knowledge — and the government is not required to prove knowledge as an element of its case. Cf. id. (where the defendant has the opportunity to disprove knowledge and consent as an affirmative defense, knowledge and consent are not elements of the crime which the government must prove to establish its case).