Pakistan Legal Practitioners and Bar Councils Rules, 1976 — section 49

49. A voter who has inadvertently spoiled his ballot paper so that it cannot be used may, after satisfying the Polling Officer about the fact of inadvertence, return the ballot paper to the Polling Officer, who shall issue another ballot paper after cancelling the spoiled paper which shall be placed in a packet labeled "spoiled ballot papers" noting the fact of cancellation on the counterfoil also.