Can a witness refuse to answer a question in a civil proceeding if it would incriminate her on a unrelated criminal matter?

Question

Basically the title. I saw on a lawyer drama that a witness was compelled to answer because it was not a criminal case. But if the truthful answer uncovers a criminal matter that would incriminate the witness, can she refuse to answer on grounds of Fifth Amendment, even if it is civil case?

Answer 1

In McCarthy v. Arndstein, 266 U.S. 34, the Supreme Court declared that

The privilege is not ordinarily dependent upon the nature of the proceeding in which the testimony is sought or is to be used. It applies alike to civil and criminal proceedings, wherever the answer might tend to subject to criminal responsibility him who gives it.

Kastigar v. United States, 406 U.S. 441 It can be asserted in any proceeding, civil or criminal, administrative or judicial, investigatory or adjudicatory, [Footnote 10] and it

Page 406 U. S. 445 likewise finds that the privilege

can be asserted in any proceeding, civil or criminal, administrative or judicial, investigatory or adjudicatory, and it protects against any disclosures that the witness reasonably believes could be used in a criminal prosecution or could lead to other evidence that might be so used.

There may be some confusion over criminal vs. civil cases, so first we should restate the self-incrimination clause:

nor shall be compelled in any criminal case to be a witness against himself

There are many ways that this language can be interpreted, for example it could mean that a person who is a criminal defendant cannot be compelled to testify against themselves in that case; or that the protection applies to a possible, future criminal case against them (when they are the defendant in a criminal trial); or when they are a non-defendant witness in some criminal trial. Instead, the courts interpret the privilege as protection against any being compelled to testify, when that testimony has a tendency to incriminate.

The line that exists, w.r.t. civil cases, is that you can be compelled to testify against your civil case interest – you can be compelled to testify that you breached a contract, for example. When testifying in a criminal case, you can be compelled to testify to a breach of contract. It is not about the nature of the case where you are testifying, it is about the nature of the possible case where that testimony could be used against you.