What is the punishment for swearing falsely, and is expiation due for it, and is it permissible to swear falsely to salvage a specific situation?

Swearing a false oath is forbidden and considered among the major sins. It necessitates repentance and the restoration of rights to their owners, and it does not require expiation. However, swearing a false oath may cease to be forbidden if one is coerced, and it may sometimes become obligatory to save an innocent life from perishing.