United States v. Hubbell is a landmark Supreme Court case from 2002 that addressed the scope of the Fifth Amendment's protection against self-incrimination in the context of subpoenas. The Court ruled that when a defendant produces documents in response to a subpoena, and those documents are potentially incriminating, the act of producing them can itself be considered a form of self-incrimination, thus offering protection under the Fifth Amendment. This case highlighted the delicate balance between law enforcement's ability to gather evidence and an individual's right against self-incrimination.