D.C. Mun. Regs. r. 4-423
Testimony of all witnesses shall be given under oath or affirmation.
The order of examination of witnesses shall be direct, cross, redirect, and recross.
The hearing examiner shall exclude from the hearing room all witnesses who have not yet testified, while any other witness is testifying. Parties who will testify shall not be subject to this requirement. The hearing examiner shall admonish all persons present during the rendering of testimony to refrain from discussing that testimony with any witness yet to testify, and shall admonish witnesses who have yet to testify to refrain from discussing testimony already rendered with any person present during the rendering of that testimony. Any person failing to comply with the hearing examiner's instructions in this connection shall be subject to the sanctions in § 434.3(d).
D.C. Mun. Regs. r. 4-423