Without prejudice
A label put on settlement offers and negotiation letters so they cannot be shown to a court if talks break down.
Definition
"Without prejudice" is a rule of evidence that protects genuine settlement negotiations from being used as admissions in later court proceedings. A letter or conversation marked "without prejudice" cannot normally be produced in evidence. The rule applies automatically to genuine offers to settle; the label itself does not create protection if the communication is not a genuine attempt to compromise. "Without prejudice save as to costs" is a variant that allows the document to be shown to the court once liability is decided, to argue about who should pay costs.
In practice
Do not put "without prejudice" on a formal legal notice (such as a letter before action) — it may prevent the court from seeing it when you need it to. Keep "without prejudice" negotiations in separate correspondence from open communications.