What does it mean to "countersign" in a legal context?

In a legal context, to "countersign" means to sign a document that has already been signed by another person, typically as a form of validation or endorsement. This action often indicates that the countersigner agrees to the terms of the document or is formally acknowledging their authority regarding its contents. For instance, in bail bonding, the bail agent might countersign a bond to affirm that they are taking responsibility for the terms of the bail agreement.

The other responses relate to different legal actions, such as notarization—which involves a certified acknowledgment by a notary public—and preparing affidavits or filing petitions, which are distinct activities that involve creating or submitting legal documents. Each of these actions has its own specific legal functions and implications, separate from the concept of countersigning.