When you're under oath, lying can lead to charges of perjury, which is a serious crime.

Legal Consequences

'Under oath' often happens in a formal setting, like a court, where a legal oath is administered.

Courtroom Formality

Being under oath signifies that your statements carry the weight of honesty expected by society.

Using 'on oath' in a non-legal context emphasizes a personal commitment to truth and seriousness.

'On oath' can add emotional gravity to a promise, making it feel as significant as a legal pledge.

'On oath' implies a strong moral obligation to act or speak in accordance with honesty.