Retrospective criminal liability cannot arise from a later sales tax rule amendment for an earlier filing omission.

An amendment to the sales tax rules could not retrospectively impose criminal liability for a failure to file a return when no such obligation existed at the time of the alleged omission. The court held that a later change in Rule 11 could not be used to convert a past act or omission into an offence, as criminal liability must exist under the law in force when the conduct occurred. The conviction was therefore unsustainable because the amendment could not create retrospective criminal liability.

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Issues: Whether an amendment to the sales tax rules made during the course of the proceedings could retrospectively create liability for failure to submit a return and sustain a conviction for an act or omission committed before the amendment.

Analysis: At the time the charge was laid, the petitioner was not required under the Act to file any return. The subsequent amendment of Rule 11 was relied upon to treat the petitioner as liable, but an amendment made in a later year could not be used to fasten criminal liability for an earlier period. A rule may operate retrospectively for other purposes only if the law so permits, but it cannot be applied to convert a past omission into an offence.

Conclusion: The conviction could not be sustained, and the petitioner succeeded on the ground that the amendment could not create retrospective criminal liability.

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