[154] Pub. L. No. 95-225, 92 Stat. 7 (1978) (codified as amended at 18 U.S.C. 2251-2253).
Prior to 1977, only six states had provisions specifically prohibiting the use of minors in obscene materials or performances. See Child Pornography and Sex Rings, supra note 28, at 8.

Now, all fifty states have child pornography laws. See 720 Ill. Comp. Stat. Ann. 5/11-20.1 (West 1994 & Supp. 1998) (listing statutes of forty-seven states);
see also Juliann Whetsell-Mitchell, Rape of the Innocent 208 (1995) (noting that prior to 1977, most states did not have laws regulating the production and distribution of child pornography). For the three states not listed in the Illinois statute, see N.Y. Penal Law 263.00-.25 (McKinney 2000); S.C. Code Ann. 16-15-405 (2000); Vt. Stat. Ann. tit. 18, 2827 (2000).  

[155] 413 U.S. at 15.  

156] Pub. L. No. 95-225, 18 U.S.C. 2252(b).  

[157] See Annemarie J. Mazzone, Comment, United States v. Knox: Protecting Children from Sexual Exploitation Through the Federal Child Pornography Laws, 5 Fordham Intell. Prop. Media & Ent. L.J. 167, 174-79 (1994) (discussing congressional debates on whether it could ban non-obscene child pornography).  

[158] 458 U.S. 747 (1982).  

[159] The Court's exclusion of certain categories of expression from constitutional expression was most famously articulated in Chaplinsky v. New Hampshire, 315 U.S. 568, 571-72 (1942) (explaining limitations on free speech which are constitutional).

Justice Scalia's opinion in R.A.V. v. St. Paul, 505 U.S. 377 (1992) suggested a somewhat surprising twist on how to think about categories excluded from the First Amendment.
He called it a fiction to think that certain categories are completely banished from constitutional protection.
His opinion established limits on "underinclusive" viewpoint-based regulations of expression even when that expression existed wholly within an unprotected category - in the case of R.A.V., the category of fighting words. Id. at 387.  

[160] The materials at issue in Ferber had been found not obscene by the jury, which was instructed to consider obscenity as well as child pornography charges against the defendant. 458 U.S. at 752. Thus the issue for the Court was sharply defined.

[161] Pub. L. No. 98-292, 98 Stat. 204 (1984) (codified as amended at 18 U.S.C. 2251-2254, 2256, 2516).  

[162] Child Protection Act of 1984, Pub. L. No. 98-292, 98 Stat. 204.
The 1984 Act made other significant changes, such as increasing the maximum fines tenfold, and removing the requirement that the transmission or receipt of child pornography be done for profit, thereby targeting the growing non-commercial cottage industry.
Fines increased from $ 10,000 to $ 100,000 for a first offense. 18 U.S.C. 2251.
In addition, the law clarified that purely textual pornography did not fall within the scope of the statute; the language substituted "visual depiction" for "visual or print medium," which could be interpreted to include text: 

No reason for coverage of non-visual depictions was found in the legislative history of the Act, and no need for such coverage has been identified in the 6  years of implementation of the Act. Rather than write in an obscenity requirement for print material, it seems more approprite [sic] to simply limit coverage to visual material. 

H.R. Rep. No. 98-536, at 3 (1983). The law also added sections dealing with civil and criminal forfeiture. 18 U.S.C. 2253-2254.  

[163] H.R. Rep. No. 98-536, at 2 (1983).  

[164] H.R. Rep. No. 99-910, at 5 (1986).
In 1986, Congress again amended the law to create two new offenses involving advertising. Child Sexual Abuse and Pornography Act of 1986, Pub. L. No. 99-628, 100 Stat. 3510 (codified as amended at 18 U.S.C. 2251, 2255-2256, 2421-2423 (1986)).
 The bill banned

(1) advertising child pornography for any type of exchange and

(2) advertising seeking participation in any sexually explicit conduct for the purpose of creating child pornography.

It also clarified that "visual depiction" included undeveloped film and videotape, thereby codifying a decision in which the Ninth Circuit rejected a defendant's argument that undeveloped film was not a visual depiction. Id. at 4, 100 Stat. 3511; United States v. Smith, 795 F.2d 841, 846-47 (9th Cir. 1986).  

In 1988, Congress specifically outlawed the transmission of child pornography images by computer. Pub. L. No. 100-690, sec. 7511(b), 102 Stat. 4485 (as amended 18 U.S.C. 2252 (1988)).

The 1988 Act also imposes extensive record-keeping requirements for producers of any visual depiction of sexually explicit conduct that was produced by materials mailed or shipped in interstate commerce. Id. 7513(a), 102 Stat. at 4487.
Producers of such material were required to keep elaborate records about names and ages of performers and to provide such information to authorities upon request. 18 U.S.C. 2257(a)-(c).  

The Act was found unconstitutional because the requirements were not narrowly tailored and

 "put as much, if not more, of a burden on reputable producers of adult images than on the child pornography industry." Am. Library Ass'n v. Thornburgh, 713 F. Supp. 469, 479 (D.D.C. 1989).

 The court also found that the  law's presumption that the performers were underage if the records were unavailable or incomplete violated due process. Id. at 480-81.
Congress amended the Act to address concerns raised by the court. Child Protection Restoration and Penalties Enhancement Act of 1990, Pub. L. No. 101-647, 311, 104 Stat. 4789, 4816 (codified at 18 U.S.C. 2257(d)-(e)).

The government's appeal from the District Court's decision was dismissed in part as moot because of the changes. See Am. Library Ass'n v. Barr, 956 F.2d 1178, 1186-87 (D.C. Cir. 1992).

On remand, the changes were again challenged and found to be unconstitutional, Am. Library Ass'n v. Barr, 794 F. Supp. 412, 417-20 (D.D.C. 1992), but the Court of Appeals reversed and determined that most of the provisions were constitutional. Am. Library Ass'n v. Reno, 33 F.3d 78, 88-94 (D.C. Cir. 1994).

The Court of Appeals did find that the requirement that records be kept indefinitely was unconstitutional and suggested a five-year limit. Id. at 91.
 The court also found that photo developers are not "producers" of sexually explicit material and therefore not subject to the record-keeping requirements. Id. at 93.  

Congress amended the statute again in 1996 to change the definition. See infra notes 196-200 and accompanying text.
Congress also dispensed with its  requirement that prosecutions be for possession of "three or more items" containing child pornography. Protection of Children from Sexual Predators Act of 1998, Pub. L. No. 105-314, 203(b)(1), 112 Stat. 2978 (codified as amended at 18 U.S.C. 2252A (1994 & Supp. IV 1998)).
 The new law permits prosecution for possession of a single image. Id.