Former police chief Ali Dizaei will finds out if he has successfully appealed against what he says is his "unsafe" conviction for misconduct and perverting the course of justice.
The ex-Scotland Yard commander was found guilty for a second time at a retrial in February last year. The decision on his challenge is being announced by the Lord Chief Justice Lord Judge and two other judges at the Court of Appeal in London.
Iranian-born Dizaei, 50, from Acton, west London, was first convicted of framing young businessman Waad al-Baghdadi in a street row in 2010.
He was jailed for four years, but the conviction was quashed by the Court of Appeal a year later. After the second trial he received a three-year prison sentence at London's Southwark Crown Court. This was reduced by the 15 months he had already spent behind bars and he has been released.
Dizaei was sacked by the Metropolitan Police following internal disciplinary proceedings.
During the recent hearing of his appeal, Dizaei's QC Stephen Riordan argued that his conviction was "unsafe", submitting that the judge at the second trial made an "error of law" when he refused to admit certain "bad character" evidence relating to Mr al-Baghdadi.
Mr Riordan said that because of the judge's decision to reject the application the jury "did not have all the material that it should have done".
He told the court: "We submit simply that that decision was wrong - that the reasons he gave for refusing to allow this material to be deployed were matters which more properly should have been considered by the jury."
Opposing the appeal, Peter Wright QC, for the Crown, told the court: "Here there was no error by the judge in the exercise he undertook. The decision was not wrong in law."
Mr Wright said: "We submit that in the context of the fairness of this trial, that this trial remained entirely fair and that the conviction was not unsafe."