1
general::
An unfair decision, especially one in a court of law. For example, Many felt that his being expelled from the school was a miscarriage of justice. This expression, which uses miscarriage in the sense of "making a blunder," was first recorded in 1875.
American Heritage Idioms
2
general::
Phrase(s): a miscarriage of justice
a wrong or mistaken decision, especially one made in a court of law. • Sentencing the old man on a charge of murder proved to be a miscarriage of justice. • Punishing the student for cheating was a miscarriage of justice. He was innocent.
McGrawhill's American Idioms And Phrasal Verbs