The court, it is said, decides as to the tendency of the answer, and will instruct the witness as to his privilege; 2 Phill. Ev. 417; 4 Cush. 594; 1 Den. 819. It has been held that the question whether an answer would have this tendency is to be deter- mined by the oath of the witness; 17 Jur. 398. And in point of fact, out of the ne- cessity of the case, it is a matter which the witness may be said practically to decide for himself. The witness may answer if he chooses; and if he do answer after hav- ing been advised of his privileges, he must answer in full; and his answer may be used in evidence against him for all pur- poses; 1 Greenl. Ev. §§ 451, 453; 4 Wend. 252; 11 Cush. 437; 12 Vt. 491; 20 Ν. Η. 540. It is held that a defendant who vol- untarily offers himself as a witness on his own behalf waives this privilege of refus- ing to answer a question because it may tend to criminate him; 98 N. C. 599. The objection that the answer may tend to criminate can only be made by the wit ness himself; 16 Colo. 250. See 28 Fla. 00. Whether a witness be compellable to an- swer to his own degradation or infamy is a point as to which some distinctions are to be taken: a witness cannot refuse to testify simply because his answer would tend to disgrace him; it must be seen to have that effect certainly and directly; 1 Greenl. Ev. § 456. He cannot, it would seem, refuse to give testimony which is material and relevant to the issue, for the reason that it would disgrace him, or ex- pose him to civil liability. A witness is not the sole judge whether a question put to him, if answered, may tend to criminate him. The court must see from the cir- cumstances of the case that there is rea- sonable ground to apprehend danger to the witness from his being compelled to an- swer, in order to excuse him, But if the fact once appear that the witness is in danger, great latitude will be allowed him in judging for himself the effect of any particular question; 26 Ch. Div. 294; 1 Greenl. Ev. § 454; 1 Mood. & M. 108; 4 Wend. 250; 2 Ired. 346. See 8 Misc. Rep. 159. A witness may, however, be com- pelled to testify concerning his criminal acts, when prosecution therefor is barred; 66 Vt. 302; but only after it is shown affirmatively that no prosecution is pend- ing against him; 43 N. E. Rep. (III.) 781. But it would appear that he may refuse where the question (being one put on cross- examination) is not relevant and material, aud does not in any way affect the credit of the witness; 3 Camp. 519; 13 Ν. Η. 92; 1 Gray 108. Whether a witness, when a question is put on the cross-examination which is not relevant and material to the issue, yet goes to affect his credit, will be protected in refusing to answer, simply on the ground that his answer would have a direct and certain effect to disgrace him, is a matter not clearly agreed upon. There is good reason to hold that a witness should be compelled to answer in such a case; 1 Stark. Ev. 144; 1 C. & P. 85; 2 Swanst. 216; 2 Camp. 637; 3 Yeates 429. But the whole matter is one that is largely subject to the discretion of the courts; 1 Greenl. Εν. §§ 431, 449. There seems no doubt that a witness is in no case competent to allege his own tur- pitude, or to give evidence which involves his own infamy or impeaches his most solemn acts, if he be otherwise qualified to testify; Stark. Ev. 1737. See 15 Cent. L. J. 343. The privilege given by the 5th amend- ment to the constitution, that no person shall be compelled in any criminal case to be a witness against himself, extends to a proceeding before a grand jury; 142 U. §. 547. The provision of the Interstate Commerce Commission Act, compelling parties to testify even though the evidence