South Africa’s top court on Thursday rejected an attempt to overturn a previous decision that found former president Jacob Zuma should go back to jail after being released early on medical parole.

The Constitutional Court ruling could send Zuma back to prison, two years after his initial arrest sparked widespread protests that saw at least 337 people killed.

The Department of Correctional Services said in a statement that it was studying the judgment and seeking legal advice before commenting. A spokesperson for Zuma declined to comment directly on the ruling and referred any questions to the department, noting that prison officials had sought the review.

Zuma, 81, was sentenced in 2021 to 15 months imprisonment for defying a court order to give evidence at an inquiry investigating high-level corruption during his nine years in office, which ended in 2018.

He handed himself over to authorities in July 2021, but two months later was released on medical parole due to his ill health.

Last year, the Supreme Court of Appeals found that the decision to release Zuma on early medical parole was “unlawful” and that he should return to prison to finish his sentence for contempt of court.

That ruling was challenged by the National Commissioner of Correctional Services, but the Constitutional Court on Thursday found that the challenge had “no reasonable prospects of success” and should be dismissed.