A subpoena compels the person served to comply with whatever is requested in the subpoena. Therefore if a person is compelled to appear and testify in court or other legal proceeding, they are under a legal obligation to do so. Failure to comply with a subpoena is a criminal matter for which there are penalties, including fines and jail time.However if a witness feels that their testimony may implicate them in some way in the matter at hand or even another matter there may be protection for that witness. The Fifth Amendment gives individuals the right to refuse to answer any questions or make any statements if doing so would result in establishing that the person committed a crime. This right is also known as the “privilege against self-incrimination”.  Unlike with a defendant, a witness may forced to take the stand. However once they do so they may invoke their right to “plead the Fifth”; their testimony cannot be compelled. That is, a witness may not be forced to answer any incriminating questions.