The correct answer is option 1: A confession can never be used as evidence against the accused.

Option 1 statement is not correct because a confession can be used as evidence against the accused in certain circumstances. However, for a confession to be admissible in court, it needs to be free and voluntary. If the confession was obtained under duress, coercion, or any other form of unlawful pressure, it will not be admissible as evidence.

Option 2 statement is correct, as for an individual to be tried, they must have violated an existing law. If there is no law that has been violated, there cannot be a trial or punishment.

Option 3 statement is also correct, as it is protected by the principle of double jeopardy. This means that an individual cannot be tried and punished for the same offence again after they have already been acquitted or convicted for that specific offence.

Option 4 statement is also correct, as the quantum of punishment must be provided in the law as it existed on the date of the commission of the offence. This ensures that an individual is not subjected to retroactive or arbitrary punishment.

In summary, the only statement that is not correct is option 1, as a confession can be used as evidence against the accused