Identify the court case in which the testimony occurred. For example, if you are writing a paper about the meaning of "best interests of the child," and you know a doctor testified in a particular case and gave his opinion that it would be in the best interests of the children to remain in the custody of their mother, you would identify the case by using the name of the mother and father and the year of their custody case.
Locate the case report, either online or in print. Cases are reported based on the names of the parties and the year of the court's decision. For example, Doe v. Smith, 1989.
Read the case to find the page where the judge refers to the testimony you want to use in your research paper. Look for identifying phrases such as "the witness testified as follows" or "he gave the following evidence." Make a note of the volume number of the case report and the page number of the testimony. This information does not always present itself in the decisions of lower courts. Check if the case has been appealed to a higher court, because the summaries in appeal cases reference the actual trial transcripts, and you will have a better chance of finding the actual words in the appellate case report.
Ensure you use the actual words of the witness, rather than how the judge describes the evidence of the witness. Put the words of the witness in quotation marks.
Cite the in-text reference putting in brackets the names of the parties followed by a comma and then by the year. For example, "(Adams v. Hendriks, 2011)." The names are in italics.
Reference the case in the sources for your paper. For example, in an American Psychological Association-style paper, reference as: "Smith v. Smith, 25 U.S., 291 (1989)." (Smith and Smith is italicized.) This citation breaks down as follows: the parties in the case are Smith and Smith; 25 is the volume number; U.S. is U.S. Supreme Court Reports; 291 is the page number in volume 25 of the U.S. Supreme Court reports where the testimony is referred to by the judge; and 1989 is the year the case was decided.