Under 1921.19(a), when may testimony of a witness be taken by deposition in OSHA proceedings?
Yes — testimony of any witness may be taken by deposition for good cause once a complaint has been filed, whether the complaint is at issue or not.
Depositions may be taken orally or by written interrogatories before a person designated by the hearing examiner who has authority to administer oaths. See 1921.19(a) and the general 1921 overview.