Well, I tried to research Senate committee rules to no avail. All I can say for sure is that the committee would be investigative, able to subpoena witnesses and to swear witnesses. As far as it being an adversarial proceeding, it is probable that the committee's jurisdiction only extends to asking a federal judge to rule on a witness's possible perjury. I think it is unusual that a committee would target an individual. That being the case, Tom should have realized that the committee must have had what it believed was inculpatory evidence against Michael and for Michael to take the fifth regardless of Michael's desire to appear legitimate.