In a civil case, is the plaintiff's attorney allowed to withhold evidence until the deposing of the defendant's witness?
The answer will depend on the facts in each case, such as the type of evidence and purpose it is introduced for. Local and state rules require the exchange of certain evidence, such as witness lists and expert reports, etc. However, a party is not required to disclose their entire trial strategy to the other. A party is generally not required to disclose in advance evidence obtained prior to a deposition. It is possible for information to be obtained and not requested in discovery that may be used to rebut a claim or a witness' credibility.
The following is an example of a court rule:
A party shall not require a deponent to produce or submit for inspection any writing obtained or prepared by the adverse party, the adverse party's attorney, surety, indemnitor, or agent in anticipation of litigation and in preparation for trial unless the court otherwise orders on the ground that a denial of production or inspection will result in an injustice or undue hardship; nor shall the deponent be required to produce or submit for inspection any part of a writing which reflects an attorney's mental impressions, conclusions, opinions, or legal theories, or, except as provided hereinafter and in Rule 35, the conclusions of an expert engaged in anticipation of litigation and in preparation for trial. A party may require any other party to disclose the names and addresses of proposed expert witnesses; except as provided in Rule 35 such disclosure shall be solely for the purpose of enabling the party to investigate the qualifications of such witnesses in advance of trial, unless the court orders the taking of the deposition of such witnesses by any party on the ground that lack of such deposition will result in an injustice or undue hardship. Such order shall issue only on motion after hearing and shall be on such terms and conditions as the court may determine. In an action for personal injury or property damage arising out of negligence, a party may require any other to disclose the policy limits of his or her liability or property damage insurance. Such disclosed matter shall not be introduced in evidence but shall be used solely for the purpose of enabling the party to evaluate the advisability of making or accepting an offer of settlement.