Googe says if a letter starts with the phrase, then nothing in the letter can be used as evidence or against the writer? I this right? So it's a scape goat?
In South African law, the words have no real magic. Any correspondence, whether marked as "without prejudice" or not, which is in contemplation of settlement of a dispute is inadmissible as evidence.
Marking it "without prejudice" just makes it easier to identify/defend etc.
Something marked "without prejudice" is admissible as evidence when not in contemplation of settlement of a dispute.