Final answer:
The Supreme Court ruled in United States v. American Library Association that public libraries must employ filtering software to comply with the Children's Internet Protection Act.
Step-by-step explanation:
In United States v. American Library Association, the Supreme Court, in a 6-3 decision, held that public libraries must purchase filtering software and comply with all portions of the Children's Internet Protection Act. This decision was based on the idea that while the Internet offers a wide array of information and opportunities for communication, it also poses new challenges for First Amendment rights, particularly when it comes to protecting children from obscene or harmful material. The ruling recognizes the right of public libraries to implement filters to prevent minors from accessing inappropriate material, while also acknowledging the complexities of regulating speech in the digital age.