South African prosecutors want Oscar Pistorius to be tried again for killing his girlfriend Reeva Steenkamp - arguing he should have been found guilty of murder.
The double-amputee Olympic runner was convicted of manslaughter for shooting Steenkamp through a toilet door of his home.
He is currently serving a five-year sentence for manslaughter in a prison in central Pretoria.
His case is expected to before the Supreme Court of Appeal at a date to be set in November, where state prosecutors will seek a retrial.
The judges then have the power to do three things:
Reject the prosecution appeal and rule the verdict was correct
Order a retrial
Convict him of murder themselves
A murder conviction would carry a minimum sentence of 15 years.
Lawyers for Pistorius say prosecutors are wrong to challenge the original verdict and were using the appeal to persist with a "failed case".
They also said Pistorius could not afford to pay for a new trial and that it would be prejudiced because of all the media coverage.
Prosecutors claim Judge Thokozile Masipa misinterpreted parts of the law and ignored important evidence during the trial.
Their appeal hinges on part of South African law known as "dolus eventualis".
This is where someone can be found guilty of murder with lesser intent if they acted with the knowledge that a person might be killed because of their actions, but went ahead anyway.