, explicitly or implicitly, relate a factual assertion or disclose information. Only then is a person compelled to be a 'witness' against himself." Poe v. United States. 487 U.S., at 209-210, 108 S.Ct. 2341. (footnote omitted). FN20. See App. 62-70. Thus, for example, after respondent had been duly sworn by the gr