Right Against Self-Incrimination

The Fifth Amendment to the U.S. Constitution gives individuals the right to refuse to answer any questions or make any statements, when to do so would help establish that the person committed a crime or is connected to any criminal activity. This right is also known as the Fifth Amendment privilege against self-incrimination, which is invoked when someone is said to "plead the Fifth".
Can a Criminal Defendant be Forced to Testify at Trial?
At trial, the Fifth Amendment gives a criminal defendant the right not to testify. This means that the prosecutor, the judge, and even the defendant's lawyer cannot force the defendant to take the witness stand at trial, if he or she does not want to do so. Furthermore, when a defendant exercises his or her right not to testify, the jury is not permitted to take that refusal into consideration when deciding whether the defendant is guilty of the crime(s) charged.
It is important to note that, once a defendant does take the stand and testify at trial, he or she cannot ordinarily choose to answer some questions but not others. Rather, the defendant's Fifth Amendment privilege is deemed waived through the act of testifying.
Does the Privilege Apply to Fingerprints and Blood Tests?
The Fifth Amendment right against self-incrimination does ensure that a defendant in a criminal case cannot be forced to testify and "be a witness against himself or herself". But it does not apply when a defendant is fingerprinted, or made to provide a DNA sample in connection with a criminal case. In other words, a defendant may not refuse to submit to these procedures by asserting the Fifth Amendment privilege.
Who Can Claim the Fifth Amendment Privilege at Trial?
At a criminal trial, it is not only the defendant who enjoys the Fifth Amendment privilege. Witnesses who are asked to testify can refuse to answer certain questions by asserting their Fifth Amendment rights, if to answer would implicate them in any type of criminal activity. Unlike defendants in a criminal case, who have the right not to take the witness stand at all, a witness may be forced to testify (by subpoena or other means) but may exercise his or her Fifth Amendment right by refusing to answer certain questions.