Final answer:
The legal basis for the Supreme Court's decision in this case was the First Amendment, which protects freedom of the press.
Step-by-step explanation:
The legal basis for the Supreme Court's decision in this case was The First Amendment. The First Amendment protects freedom of the press, which includes the right to publish information that is of public concern. In this case, the Pentagon Papers were classified documents that revealed important information about the government's actions in the Vietnam War. The Supreme Court ruled that the government could not suppress the publication of this information, as it would violate the First Amendment rights of the press.
Learn more about Freedom of the Press