Jonathan is widely regarded as one of the best juniors at the Criminal Bar. He is the “go-to junior” for legally and factually complex cases such as those involving offences of terrorism, homicide, serious organised crime, complex fraud and cyber-crime.
He has been instructed in some of the most high-profile cases in the criminal courts, which include the recent prosecutions of John Worboys, the PC Harper trial and the trial concerning the manslaughter of 39 Vietnamese migrants. He brings to all cases his fierce intellect, unstinting hard work and dedication and an approachable and down-to-earth manner. He is much admired for his excellent and incisive judgment and legal knowledge as well as his ability to communicate complex evidence in a way that is clear and attractive to juries.
Jonathan is ranked as a leading junior in Chambers & Partners UK Bar Guide 2021 (Band 1) and the Legal 500.
He is Junior Treasury Counsel, based at the Central Criminal Court having been appointed by the Attorney-General in November 2017.
R v Shaikh and anor  EWCA Crim 45 – Approach to calculating minimum term in life sentences imposed for terrorist offending
R v Long, Bowers and Cole  EWCA Crim 1729 – Interaction between the offences of causing death by dangerous driving and unlawful act manslaughter.
McIntyre  4 WLR 144 – Sentencing powers of Court-Martial on an elected trial
Riley  EWCA Crim 816 – Role of the Attorney General as guardian of the public interest
Zaheer  1 Cr App R (S) 14 – Appropriate level of adjustment in sentence for attempts
James  1 WLR 2749 – Special Court convened to consider procedure on renewed applications to appeal
Thompson  1 WLR 4429 – 5-Judge Court of Appeal considered extended sentence provision
Muss  1 Cr App R S 17 – Level of sentence for large-scale DDoS attacks
Jonathan Polnay, led by Lisa Wilding QC secured convictions in a missing body murder trial at Cambridge Crown Court.
17 year old Bernadette Walker disappeared on 18th July 2020 after alleging that her step-father, Scott Walker, had been sexually abusing her for a number of years. She was last seen having been collected from her grandparents’ house by Walker who claimed she had simply walked away following an argument.
Walker and Bernadette’s mother, Sarah Walker, were also found guilty of perverting the course of justice by using the dead girl’s phone to send messages suggesting she was still alive and lying to the police about her disappearance.
Bernadette’s body has never been found. The trial lasted 6 weeks.
Jonathan Polnay, led by William Emlyn Jones, prosecuted eight men for conspiracy to facilitate illegal immigration and 39 counts of manslaughter, arising out of the death of Vietnamese migrants in a sealed lorry trailer.
Prosecution of three young men for the homicide of Thames Valley Police Officer, PC Andrew Harper, who was tragically killed whilst trying to apprehend thieves. (Leaders, Brian Altman QC, and then Jonathan Laidlaw QC).
Jonathan Higgs QC leading Jonathan Polnay represented a defendant in the much publicised Old Bailey trial involving the worldwide sale of "fake" bomb detection devices. Instructed by Gary Bloxsome of Blackfords LLP.
Jonathan Polnay was led by Brian Altman QC (first trial) and Jonathan Laidlaw QC (second trial) in the prosecution of three young men for killing PC Andrew Harper, whilst trying to escape with a stolen quad bike.
Mark Heywood QC and Jonathan Polnay acted for the Crown in the case of Theodore Johnson whom was sentenced to life with a minimum tariff of 26 years, increased on appeal against Unduly Lenient Sentence, to 30 years in March 2018. Johnson had been convicted previously for the manslaughters of his partners in 1981 and 1993. His third victim, Angela Best, was murdered with a claw hammer in her flat in North London in December 2016.
Jonathan Polnay prosecuted this young women who was charged with the first ever prosecution under the Biological Weapons Act and attempted murder of her mother, after attempting to poison her, taking her inspiration from the series "Breaking Bad".
‘He is highly intelligent; he is prolifically hard-working and has endless stamina and he is a great strategist and his judgment is pretty perfect. He is one of the best junior Treasury Counsel at the Old Bailey. A masterful advocate; he makes winning look easy.’
Legal 500 2021
Has the ability to simplify complex prosecution cases that might be strong evidentially but are on paper difficult to communicate to a jury." "He is good with the jury and is also someone whose judgement you can trust.’
Chambers & Partners 2021
“He has extensive experience of how the criminal justice system operates in practice, particularly in relation to the processes used by law enforcement and the mechanics of the various powers available to law enforcement agencies. He has excellent judgement and is able to offer simple, but highly useful suggestions.”
Chambers UK 2020
"There are not enough superlatives to do this gentleman justice; he has a prolific energy that galvanises his cases."
Chambers UK 2019
"He instils great confidence in clients."
Legal 500 2016
‘A very effective prosecutor, and also a very hardworking defence junior, who gets on very well with clients.’
Legal 500 2017
‘A masterful advocate – eloquent, sharp and irresistibly persuasive.’
Legal 500 2020