At the trial or upon any hearing, a part or all of a deposition, so far as otherwise admissible under the rules of evidence, may be used a substantive evidence if the witness is unavailable, as defined in § 70.75, or the witness gives testimony at the trial or hearing inconsistent with his deposition. Any deposition may also be used by any party for the purpose of contradicting or impeaching the testimony of the deponent as a witness. If only a part of a deposition is offered in evidence by a party, an adverse party may require him to offer all of it which is relevant to the part offered and any party may offer other parts. NOTE: Section 70.70 is based on former Rule 15(e) and former § 1345. There are, however, certain differences. First, Aunavailability@ is now defined by § 70.75 as including situations where the witness is physically present but is exempted from testifying, refuses to testify or testifies to a
lack of memory. None of these grounds was stated under former law, but have been used. Section 70.75 also makes clear that a witness's disability may be either physical or mental. See former § 1345 (insanity). Also, Subsection (b) of &70.75 qualifies the grounds of unavailability by providing that a deponent is not available where Ahis exemption, refusal, claim or lack of memory, inability or absence is due to the procurement of wrongdoing of the proponent of his deposition ... No such qualification was stated in former § 1345 and that stated in former Rule 15(e) was arguably not so encompassing. Finally, § 70.70 provides that a deposition may be used as substantive evidence both where the deponent is unavailable and where his testimony at trial is inconsistent with his deposition.