last resort
noun
A final course of action, used only when all else has failed: asking them to leave the school should be a last resort [as modifier]: a last-resort treatment for lung cancer...
- Court action was, however, a last resort.
- War should in any case always be a last resort in settling an international conflict.
- In most cases, pesticides should be considered the last resort for reducing losses due to pests.
Phrases
as a first (or last or final) resort
in the last resort