D.C. Mun. Regs. tit. 4, r. 4-424
When a witness is unavailable, as defined by the Civil Rules of the Superior Court of the District of Columbia, to testify in person, or upon the agreement of the parties, the hearing examiner may admit the content of the proffered testimony in an alternate form, such as the following:
The hearing examiner shall require the party seeking the admission of the alternate form of testimony to provide notice and evidence of the witness unavailability, as well as a proffer of the relevance of the testimony.
In the absence of the parties' agreement as to admissibility of an alternate form of testimony of a witness not subject to the subpoena power of the Commission, the hearing examiner may exclude the testimony if the rights of the opposing party would be substantially prejudiced by its admission into evidence.
With the exception of non-hearsay deposition testimony, the hearing examiner shall give testimony admitted into evidence under this section the same weight as other hearsay evidence.
D.C. Mun. Regs. tit. 4, r. 4-424