Cite as: 542 U. S. 656 (2004) Opinion of the Court software is an alternative that is less restrictive than COPA, and, in addition, likely more effective as a means of restricting children's access to materials harmful to them. The District Court, in granting the preliminary injunction, did so primarily because the plaintiffs had proposed that filters are a less restrictive alternative to COPA and the Government had not shown it would be likely to disprove the plaintiffs' contention at trial. Ibid. Filters are less restrictive than COPA. They impose selective restrictions on speech at the receiving end, not universal restrictions at the source. Under a filtering regime, adults without children may gain access to speech they have a right to see without having to identify themselves or provide their credit card information. Even adults with children may obtain access to the same speech on the same terms simply by turning off the filter on their home computers. Above all, promoting the use of filters does not condemn as criminal any category of speech, and so the potential chilling effect is eliminated, or at least much diminished. All of these things are true, moreover, regardless of how broadly or narrowly the definitions in COPA are construed. Filters also may well be more effective than COPA. First, a filter can prevent minors from seeing all pornography, not just pornography posted to the Web from America. The District Court noted in its factfindings that one witness estimated that 40% of harmful-to-minors content comes from overseas. Id., at 484. COPA does not prevent minors from having access to those foreign harmful materials. That alone makes it possible that filtering software might be more effective in serving Congress' goals. Effectiveness is likely to diminish even further if COPA is upheld, because the providers of the materials that would be covered by the statute simply can move their operations overseas. It is not an answer to say that COPA reaches some amount of materials that are harmful to minors; the question is whether it would reach more of them than less restrictive alternatives. In