Cite as: 542 U. S. 656 (2004) Opinion of the Court trial. There is a potential for extraordinary harm and a serious chill upon protected speech. Cf. id., at 817 ("Error in marking that line exacts an extraordinary cost"). The harm done from letting the injunction stand pending a trial on the merits, in contrast, will not be extensive. No prosecutions have yet been undertaken under the law, so none will be disrupted if the injunction stands. Further, if the injunction is upheld, the Government in the interim can enforce obscenity laws already on the books. Second, there are substantial factual disputes remaining in the case. As mentioned above, there is a serious gap in the evidence as to the effectiveness of filtering software. See supra, at 668. For us to assume, without proof, that filters are less effective than COPA would usurp the District Court's factfinding role. By allowing the preliminary injunction to stand and remanding for trial, we require the Government to shoulder its full constitutional burden of proof respecting the less restrictive alternative argument, rather than excuse it from doing so. Third, and on a related point, the factual record does not reflect current technological reality-a serious flaw in any case involving the Internet. The technology of the Internet evolves at a rapid pace. Yet the factfindings of the District Court were entered in February 1999, over five years ago. Since then, certain facts about the Internet are known to have changed. Compare, e. g., 31 F. Supp. 2d, at 481 (36.7 million Internet hosts as of July 1998), with Internet Systems Consortium, Internet Domain Survey, Jan. 2004, http:// www.isc.org/index.pl?/ops/ds (as visited June 22, 2004, and available in Clerk of Court's case file) (233.1 million hosts as of Jan. 2004). It is reasonable to assume that other technological developments important to the First Amendment analysis have also occurred during that time. More and better filtering alternatives may exist than when the District Court entered its findings. Indeed, we know that after the District Court entered its factfindings, a congressionally ap-