The public services card was brought in as a way of accessing welfare services.
The findings of the report by the Data Protection Commissioner were made known in August however the full rationale for the decision will be made public later.
Commissioner Helen Dixon ruled the state must delete data held on more than 3 million citizens because there is no basis in law for holding on to it.
She found there no legal reason to make people get the card to access state services like getting a driving licence or a college grant.
The government is to challenge the decision in the courts.