Immunity from prosecution for an individual is generally sought when that individual has information necessary to the public interest, but has refused or is likely to refuse to testify or provide the information on the basis of the privilege against self-incrimination. There are different types of immunity that may be granted in exchange for a person's testimony.
Transactional immunity bars any subsequent action against the immunized person, regardless of the source of the evidence against that person. Testimonial or "use" immunity is generally preferred because it does not prevent the government from prosecuting the person based on independently-acquired evidence.
