Almost always used with 成为 or 成了 (become) - the whole point is that something written (law, contract, promise) has become worthless. Strongly negative, often used to criticize governments or institutions for non-enforcement.
memory
一 (one) 纸 (sheet of paper) 空 (empty) 文 (text) - literally 'one sheet of empty writing.' The imagery is a page with words on it but no power behind them.
