The value of interpreter certification, moreover, depends on the validity of the testing methodology and other certification requirements. Some states use court interpreter examinations that are of dubious validity. Federal certification is usually a good indicator of competence. State certification may or may not be a reliable indicator, depending on the state in question. It is a good sign if a translator you are considering is accredited by the American Translators Association in the appropriate language combination.
Reliable certification is one of the most important issues of the day.
The written examination is slated for November 2001, and the oral is to be administered in February 2002. The only languages for which there is federal court certification are Haitian Creole, Navajo and Spanish. This is a question of ethics and technique. If an interpreter is interpreting for a witness and that witness says something that the interpreter does not understand, the interpreter is obligated to seek clarification, after asking the judge's permission. If the interpreter is simultaneously interpreting the proceedings, the answer depends on whether the importance of the thing said seems sufficient to outweigh the intrusiveness of interrupting the proceedings to request a repetition or clarification, and that determination depends on the interpreter's judgement.