Striking down key provisions of the Children’s Internet Protection Act as unconstitutional, a special three-judge U.S. District Court panel in Philadelphia has ruled that Congress went too far when it threatened to pull certain federal funds from any public library that failed to install “filtering” software to block access to sexually explicit Web sites.

The judges found that the law runs afoul of the First Amendment because filtering software simply blocks too much and that mandating its use would therefore force libraries to censor the speech of millions of Internet speakers.