735 ILCS 5/8-401
Where in any action or proceeding, the claim or defense is founded on a book account or any other record or document, any party or interested person may testify to his or her account book, or any other record or document and the items therein contained; that the same is a book, record, or document of original entries, and that the entries therein were made by himself or herself, and are true and just; or that the same were made by a deceased person, or by a disinterested person, a non-resident person of the state at the time of the trial, and where made by such deceased or non-resident person in the usual course of trade, and of his or her duty or employment to the party so testifying; and thereupon the account book and entries or any other record or document shall be admitted as evidence in the cause. Where such book of original entries or any other record or document has been photographed, microphotographed, microfilmed, optical imaged, or otherwise reproduced either in the usual course of business, or pursuant to any statute of this State authorizing the reproduction of public records, papers or documents, and the reproduction, in either case, complies with the minimum standards of quality for permanent records approved by the State Records Commission, then such reproduction shall be deemed to be an original record, book or document for all purposes, including introduction in evidence in all courts or administrative agencies.
735 ILCS 5/8-401