She refuses to call him as a witness, though he would have given testimony helpful to her client. As a paralegal interviewing potential witnesses or preparing witnesses for trial, you too may be in a situation, in either a civil or criminal context, where you suspect the witness is not completely forthright and his or her testimony may not be truthful. NFPA's Model Code of Ethics and Professional Responsibility addresses this issue in several places. Even in the civil context, perjury can be a criminal act. It is important to read and understand your state's perjury statutes.
Every witness has the potential to alter information.
Therefore, it is important as an interviewer to word questions in a neutral tone so that the information you receive from the witness is complete and truthful. The important task of gathering accurate information to assess your client's claim can set you off on the right foot. Including a question in the interview about negative information the witness may have about your client can also give you a clue about the willingness of the witness to provide truthful information. It is important, as an interviewer, to be on the lookout for instances of embellishment or omission that might appear to be beneficial to your client. Sometimes it is not until you have interviewed a witness several times that you conclude the information provided by the witness might not be entirely accurate.