Which United States Supreme Court case is correctly paired with the constitutional amendment on which it focused?

The case of Citizens United v. Federal Election Commission is correctly associated with the First Amendment because it addresses the issue of free speech in the context of political spending by corporations and unions. The Supreme Court ruled that restrictions on independent political expenditures by these entities constitute a violation of the First Amendment's guarantee of free speech. This landmark decision significantly changed the landscape of campaign finance by affirming that political spending is a form of protected speech under the First Amendment, thus enabling corporations and unions to spend unlimited amounts in support of candidates or issues.

In examining other choices, the Hazelwood case pertains to the First Amendment as it involves the rights of students and the limitations on free speech in a school environment; however, it is not correctly paired with the Fourth Amendment. The U.S. v. Nixon decision revolves around the principle of executive privilege and does not directly involve the First Amendment but highlights issues around due process and the balance of powers. Lastly, Bush v. Gore relates to electoral processes and does not connect with the Fourth Amendment, which focuses on unreasonable searches and seizures.