Русско-англо-русский юридический словарь

The appeal court will allow an appeal where the decision of the lower court was either:

• Wrong (in that it erred in law or in fact or in the exercise of its discretion).
• Unjust because of a serious procedural or other irregularity in the proceedings in the lower court.

The court allowed the appeal on the grounds of mercy "in the light of the deterioration in the appellant's condition post-dating the sentence". (BBC News)