Why do you raise your right hand when you swear an oath in testifying?
Answer:
The chief purpose of such an act is for ceremony or solemnity, and the act does not of itself make an oath.
http://www.tmcec.com/benchbook06/12-oath...
In a court of law the witness swears to tell the truth, the whole truth, and nothing but the truth. That is an assumed obligation. He ends ' so help me God ' which is the oath, attesting to the sincerity of his obligation. In taking both obligation and attesting it by the oath, the witness is required to raise his right hand, a curious throwback to ancient days in which a man offered his right hand to be cut off if his oath was broken.



