Illinois Supreme Court Rule 212 (Use of Depositions)
There are four main reasons or purposes for which a discovery deposition may be taken:
(1) for impeaching the testimony of the deponent as a witness in the same manner and to the same extent as any inconsistent statement made by a witness;
(2) as an admission made by a party or agent of a party in the same manner and to the same extent as any other admission made by that person;
(3) if otherwise admissible as an exception to the hearsay rule; and
(4) for any purpose for which an affidavit may be used

