(a) General rule.--Every witness, before giving any testimony shall take an oath in the usual or common form, by laying the hand upon an open copy of the Holy Bible, or by lifting up the right hand and pronouncing or assenting to the following words: 'I, A. B., do swear by Almighty God, the searcher of all hearts, that I will , and that as I shall answer to God at the last great day.' Which oath so taken by persons who conscientiously refuse to take an oath in the common form shall be deemed and taken in law to have the same effect as an oath taken in common form. (b) Right to affirm.--The affirmation may be administered in any judicial proceeding instead of the oath, and shall have the same effect and consequences, and any witness who desires to affirm shall be permitted to do so.
Pennsylvania Legal Code