Via Isabella Massardo (Taccuino di traduzione), an article about court interpreters in the U.S. state of Georgia, in the Atlanta Journal-Constitution. The article gives a general survey of the numbers of interpreters required and how they are used.
bq. In one recent case, a victim robbed by three juveniles required a Spanish translator. While the victim testified about how she identified one assailant, the translator mixed up the gender of a crucial word. The interpreter asked her how many people she was shown in a lineup, rather than how many males she was shown, explained Marina Navia, a victims’ advocate with the Fulton County district attorney. The resulting confusion contributed to the case’s dismissal.
On this subject, see also the website of NAJIT, The National Association of Judiciary Interpreters and Translators.