Once you have exhausted the witness’ knowledge regarding their knowledge of the subject matter of the dispute, filled in the gaps, and created usable testimony by gaining recapitulation and are about to conclude the deposition, you want to do all that you can to make sure the witness cannot later change testimony without looking biased or lacking in veracity.  Consider asking the following questions which will provide you with some good testimony in the event the witness attempts to materially change his or her testimony at the time of trial:

• Witness, do you agree that I have given you every opportunity to tell me what you want the court to know about the incident leading to this suit?
• Do you agree that you have given me truthful testimony today?
• Is there anything that you think is important about the incidents related to this lawsuit that I have not asked you about?
• If there is, please tell me about that now.
• So, you have told me everything that you believe is important about this lawsuit?

Gaining this testimony will not prevent the witness from changing testimony, but it will allow you to highlight the fact that the witness didn’t think the “new” testimony was important at the time of the deposition, and allow you to argue that the trier of fact should discount the testimony for that reason.