(c) No person shall be permitted to testify as a witness at the hearing, or pursuant to deposition or interrogatory under § 725.458, unless that person meets the requirements of § 725.414(c).

1. (1) In the case of a witness offering testimony relevant to the liability of the responsible operator, in the absence of extraordinary circumstances, the witness must have been identified as a potential hearing witness while the claim was pending before the district director.
2. (2) In the case of a physician offering testimony relevant to the physical condition of the miner, such physician must have prepared a medical report. Alternatively, in the absence of a showing of good cause under § 725.456(b)(1) of this part, a physician may offer testimony relevant to the physical condition of the miner only to the extent that the party offering the physician's testimony has submitted fewer medical reports than permitted by § 725.414. Such physician's opinion shall be considered a medical report subject to the limitations of § 725.414.