Any party to suit can call documents from other party .Order 11 rule 12 of cpc is very clear
12. Application for discovery of documents
Any party may, without filing any affidavit, apply to the Court for an order directing any other party to any suit to make discovery on oath of the documents which are or have been in his possession or power, relating to any matter in question therein. On the hearing of such application the Court may either refuse or adjourn the same, if satisfied that such discovery is not necessary, or not necessary at that stage of the suit, or make such order, either generally or limited to certain classes of documents, as may, in its discretion be thought fit:Provided that discovery shall not be ordered when and so far as the Court shall be of opinion that it is not necessary either for disposing fairly of the suit or for saving costs.
If defendant wants to call the documents from the custody of plaintiff ,he should have to file written statement firstlythen he can move application u/o 11 r 12 of cpc.