2 CFR § 180.835 - Are debarment proceedings formal?
(a) Debarment proceedings are conducted in a fair and informal manner. The debarring official may use flexible procedures to allow you as a respondent to present matters in opposition. In so doing, the debarring official is not required to follow formal rules of evidence or procedure in creating an official record upon which the official will base the decision whether to debar.
(b) You or your representative must submit any documentary evidence you want the debarring official to consider.