When a person is required or chooses to make a formal statement under oath, there are various phrases and expressions that can be used. These include, but are not limited to, "swear under oath," "affirm under penalty of perjury," "vow under oath," "attest under oath," "declare under oath," "testify under oath," "state under oath," "certify under oath," and "avow under oath." Using any of these phrases carries the weight of the legal consequences of perjury if the statement is found to be false. Therefore, it is important to choose the appropriate synonym for assert under oath based on the context and importance of the statement being made.