Sworn testimony

Sworn testimony is evidence given by a witness who has made a commitment to tell the truth. If the witness is later found to have lied whilst bound by the commitment, they can often be charged with the crime of perjury. The types of commitment can include oaths, affirmations and promises which are explained in more detail below. The exact wording of the commitments vary from country to country.
Types of commitment.
The commitment can come in different forms depending on the situation of the witness. The types of commitment used in the United Kingdom are:
Variations by country.
Canada.
"Affirmation":
India.
"Oath/Affirmation":
South Africa.
"Oath":
"Affirmation":
United Kingdom.
England and Wales.
"Oath":
"Affirmation":
"Promise":
In the UK, a person may give testimony at any age, but will not be sworn in unless 14 years old or over.
Scotland.
"Oath":
"Affirmation":
United States.
"Oath":
"Swear" may be replaced with "affirm", and either "so help you God" or "under pains and penalties of perjury" may be used; all oaths and affirmations are considered to be equivalent before the law. These modifications to the oath were originally introduced in order to accommodate those who feel uncomfortable swearing religious oaths, such as Quakers, as well as to accommodate the irreligious. In "United States v. Ward", the Ninth Circuit Court of Appeals ruled that certain other modifications of the oath were acceptable so long as they demonstrated "a moral or ethical sense of right and wrong". 
"Oath (California)":
"Oath (Washington)":
"Affirmation (Washington)":