One who makes affirmation instead of making oath that the evidence which he is about to give shall be the truth, as if he had been sworn. He is liable to all the pains and penalty of perjury, if he shall be guilty of wilfully and maliciously violating his affirmation.
A solemn declaration and asseveration, which a witness makes before an officer, competent to administer an oath in a like case, to tell the truth, as if be had been sworn.
In the United States, generally, all witnesses who declare themselves conscientiously scrupulous against taking a corporal oath, are permitted to make a solemn affirmation, and this in all cases, as well criminal as civil.
In England, laws have been enacted which partially relieve persons who, have conscientious scruples against taking an oath, and authorize them to make affirmation. In France, the laws which allow freedom of religious opinion, have received the liberal construction that all persons are to be sworn or affirmed according to the dictates of their consciences; and a quaker's affirmation has been received and held of the same effect as an oath.
The form is to this effect: 'You, A B, do solemnly, sincerely, and truly declare and affirm'. For the violation of the truth in such case, the witness is subject to the punishment of perjury as if he had been sworn.
Affirmation also means confirming; as, an affirmative statute. There's related stuff in other Library areas , so explore.