First, I am not an expert on this, so you should wait for other posters, and also go to
www.finra.org/ArbitrationMediation/index.htm and
www.nasd.com/arbitration_mediation for additional information.
An arbitrator acts much like a judge in a court of law, but arbitrators are not as strictly bound by case precedents and statutory laws as are judges. They are given a wider berth when interpreting the law. If an arbitrator determines a rule or statute has been violated, disciplinary action may follow but it is up to the arbitrator whether to seek action or not. If an arbitrator disregards the law entirely, however, a state or federal court can vacate an award.
At an arbitration hearing, all who will be testifying are sworn to tell the truth. A verbatim record of the proceeding should be kept, in the event of a dispute over what was said. Each case that comes before an arbitrator is judged on the written and oral testimonies and evidence presented. You, or your attorney if you are represented by one, may object to both the testimony and evidence. You can object to testimony that you feel is false. If you know going into arbitration that employees are going to lie, try to provide evidence that they are lying. Otherwise it will be he-said/she-said, and it will be up to the arbitrator to decide who is lying and who is not.
All decisions an arbitrator makes are final and binding, and you cannot litigate in court after arbitration.
Even in courts of law, perjured testimony (a felony) often goes without prosecution. A judge is more apt to cite the "liar" with contempt of court.
Again, wait for others to post who have MUCH more knowledge about this than I do.