Chambers is delighted that Piers Marquis, Kate O’Raghalla...Read more
Piers Marquis is best known for defending allegations of murder, terrorism and organised crime. He also specialises in defending allegations of politically motivated and protest related crime and acting for non-state core participants in Public Inquiries.
He is an experienced and committed barrister who is primarily instructed on cases of a particularly serious or complex nature. He is consistently highly ranked across the legal directories in criminal law, public inquiries and protest law. He acts as leading counsel, sole counsel and junior counsel.
"A joy to work with – collaborative, very sharp mind, insightful, brilliant with clients, excellent drafting." - Legal 500 2026
"No nonsense and straightforward in his advocacy. Piers is a star." - Legal 500 2026
"He is a brilliant advocate and an excellent strategist and has a lovely manner with clients. He is good at having the difficult conversations and is a pleasure to work with." - Chambers and Partners 2026
"Marquis always fights for the underdog with vim and vigour."- Chambers and Partners 2026
“Piers is a very gifted and tenacious barrister. He has a great manner with juries as well as both professional and lay clients. His preparation is comprehensive and his tactical awareness is very acute. He is fearless in defending his clients and is not afraid of fighting their corner. This coupled with his ability to persuade juries is why he is very much in demand.” - Legal 500 2025
“His attention to detail and sheer hard work in delving in to the most minute material make him a formidable advocate.” - Legal 500 2025
“A brilliant advocate with a fearless approach. He is an out-of-the-box thinker, great with strategy and an excellent cross-examiner. He is also excellent at constructing and presenting legal arguments, both in writing and orally.” - Legal 500 2024
"Mr Marquis is a fantastic lawyer who possesses an astute legal mind and a passion for fighting for justice for his clients." - Chambers and Partners 2023
"Piers is very bright, hard-working and gets brilliant results. He cares about and has a very good manner with clients." - Legal 500 2023
"Piers is just a top barrister — hard working, committed, unflappable and totally dedicated to the cause. He has an excellent manner with clients and is respected by all for his professional, no nonsense approach in all of his cases. He can master and assimilate vast amounts of material." - Legal 500 2022
"He is exceptional with clients and knows the law well.” – Chambers and Partners 2022
"Thoroughly prepared and excellent with both lay clients and solicitors. Jury friendly. Fights for his clients with every sinew of his body and great passion." - Legal 500 2021
"Noted for his expertise in terrorism cases. Very client-friendly and a real fighter in court." - Chambers and Partners 2021
"He fights for his clients like there is no tomorrow." - Legal 500 2020
"An “outstanding” advocate who is praised for his “first-rate” commitment to his clients." - Chambers and Partners 2020
"Absolutely tenacious when on his feet." - Chambers and Partners 2020
"A born defender, his instincts and loyalties lie firmly with the individual." - Legal 500 2018
"A popular choice for Murder and Terrorism trials." - Legal 500 2018
"He brings a commitment to his clients and to court, which is rarely seen these days." - Legal 500 2017
"He has a natural empathy with clients, which assists him in understanding the issue at hand without compromising his professionalism." - Chambers and Partners 2017
"Just fantastic at anything from Terrorism to Magistrates trials." - Legal 500 2016
Piers firmly and passionately believes in the independence of the Bar and the right of individuals to receive proper representation when faced with prosecution by the state.
Consequently since 2019, he has not been undertaking trial work under the Government’s AGFS Schemes 10, 11 and 12, which he considers to be an unacceptable continuation of a concerted effort to undermine the standards and independence of the Bar.
His most recent briefs have included murders, domestic and international terrorism, multi-million pound white-collar fraud, multi-national drugs importations/high end conspiracies to supply and cases arising from prolonged police operations targeting organised crime. Notable, more recent and successful defences include the acquittals of:
Piers has been instructed in the Undercover Policing Inquiry since 2016. He acts on behalf of a number of Non-State Core Participants, across all five tranches of the Inquiry. His clients include the Campaign for Nuclear Disarmament, the Stop the War Coalition, a former Labour Member of Parliament, Central Committee members of the Socialist Workers’ Party, Youth against Racism in Europe and the Socialist Party, and members of the Troops Out Movement and Revolutionary Communist Party of Britain (M-L). He has also acted for two of the women who were deceived and sexually exploited by undercover officers.
His opening statements to the Inquiry can be found here, here, here (T1P3), here (T1 closing), here (T2P1) and here (T2P2).
Since 2023, Piers has also been instructed on the Covid Inquiry, representing frontline health and care workers, including migrant nursing staff and outsourced non-clinical hospital and care home staff. His submissions to the Inquiry can be found here and here.
Piers’s specialisation in defending allegations of politically motivated crime, includes a particular emphasis on freedom of expression and the right to protest.
He was first instructed as leading counsel at only six years call, in the successful defence of one of the "Sequani Six" defendants, in what has been said to be the longest running animal rights trial in British legal history and the first effective trial under s.145 of the Serious Organised Crime and Police Act 2005.
He was leading counsel for three of the six imprisoned “Shrewsbury 24” pickets, (including the actor Ricky Tomlinson) in their successful appeal against that historic miscarriage of justice.
He has defended prominent Trade Unionists, pickets, political activists, Animal Liberation Front activists, hunt and badger cull saboteurs/monitors, environmental and anti-arms trade protestors, Student and London “rioters” and was instructed in a large number of the Fathers4Justice cases. He secured the only acquittals in the Bristol Stokes Croft “Tesco Riot” cases and acted for defendants in the Occupy movement, including the occupation of Trafalgar Square and the eviction of the St.Paul’s camp.
Before being called to the Bar, Piers gained considerable experience running the case preparation section in the criminal department of a solicitors’ firm in the Midlands. He also worked on civil actions against the police and cases involving gypsy rights. He also travelled extensively around the world, funding his travels with work as a scuba divemaster, English teacher and journalist.
R v E – The Defendant E was extradited from Spain in 2012, convicted of drugs importation offences and sentenced to 28 years imprisonment. The Prosecution instigated confiscation proceedings under POCA 2002 and in December 2015 secured a Confiscation Order in the sum of £13 million. A default term of imprisonment of 10 years was ordered, to be served consecutively to the 28 year sentence.
The Defendant was able to re-open the proceedings by way of the slip rule. Piers was appointed to replace previous counsel and thereafter represented E in the re-hearing of the proceedings. Following the service of further financial statements and legal submissions on behalf of the defendant a Confiscation Order of just over £36,000 was made. A default term of 12 months was imposed.
R v Warren and others, representing the actor Ricky Tomlinson, in the successful appeal against politically motivated convictions arising from the 1972 Building strike [2021] EWCA Crim 413.
R v Johnson, Khan and multiple others (R v Johnson [2017] 4 WLR, 1 Cr.App.R 12, Crim LR 216). The post-Jogee guideline case of joint enterprise.
R v Van Ek and Jukes [2013] All ER (D) 109
R v Pecco – [2010] 7 Archbold Review 3, Archbold 14-34 - Identification, armed robbery, breaches of PACE and inadequate judicial direction. Conviction quashed.
R v Modeste (A-G's ref No. 93 of 2007) [2007] All ER (D) 418 (Nov), [2007] EWCA Crim 3225) - Aggravated burglary, false imprisonment and sex offences. Sentencing.
Currie and Cresswell v D.P.P. [2006] All ER (D) 429 (Nov), [2007] Env. L.R.D8, 171 J.P. 233, Archbold 23-51
R v Kirk [2006] Crim LR 850, [2006] EWCA Crim 725, Archbold 25-353.