Kieran regularly appears as leading counsel in all categories of criminal work and in recent years has focused on the representation of Defendants charged with homicide.

Notable cases in which he has appeared include: R v Steele and Others, the Rettendon Murders (3 men shot dead in a Range Rover in Essex) which has become the subject matter of two films ‘Essex Boys’ and ‘The rise of the foot soldier’, R v Carol Peters (the appeal and re-trial) in which the Court of Appeal quashed her murder conviction (alleged tamazepan poisoning and the inflicting of 39 stab wounds) ordering a re-trial at which she was acquitted of murder (the jury accepting that she was suffering from battered women syndrome), R v Booth and Others (“Bradford four”) successful Section 3 Criminal Law Act 1967 defence (use of force in the prevention of crime) raised on behalf of animal liberators charged with causing explosions at abattoirs where animals were being cruelly treated. R v Bonner and Others (Marcus Garvey Slaying) 7 men dismember their victim in a public car park all allegedly armed with machetes. R v Chun Mo Hui, first on the indictment in a 25 handed conspiracy to Murder (victim pursued and hacked to death by 24 “14K” Triad members, ultimately having his head crushed under the wheel of a car). R v O’Connor and Ayres (“The Pescado”) six corporate manslaughter charges following the sinking of an allegedly unseaworthy fishing vessel with a young and inexperienced crew. R v Kansaran (Operation Mamba), £13 million VAT fraud. CAA v Captain Derek Hammond, pilot lands helicopter on busy pier on a mid-summer’s afternoon to collect his wife, allegedly recklessly endangering life and property.

Kieran Maidment’s  more recent practice has involved him in a number of so-called “black on black” drive-by shootings/killings including R v Powell and Others, 10 handed fatal shooting at “Donkeymans” Afro-Caribbean club, R v Hudson and Others (alleged false imprisonment and torture of a young woman leading to her death and the discovery of her body in the grounds of Newstead Abbey), R v Jeyachandran (large-scale post office fraud). R v Gill, Zubair and Others, 7 handed conspiracy to assist illegal entry into the UK alleging over 100 bogus marriages. R v Abdurrahman, 26 handed conspiracy to commit violent disorder. Two opposing Iraqi factions armed with baseball bats resolve their differences leading to fatalities. R v Gunn, McNee and Others, alleged revenge killing/execution in Lincolnshire of the mother and stepfather of Michael O’Brien, following his conviction for the murder of Marvyn Bradshaw and his outburst to the public gallery at the conclusion of his trial. R v El Rayess and Meghrabi, alleged £50 million money laundering through a bureau de change, where the proceeds of crime were said to be exchanged for a huge quantity of 500 Euro notes. R v Morgan and Others, an allegation of a series of high value armed robberies by a group of so-called “Yardies”, leading to the death of one victim and subsequent murder and conspiracy to commit armed robbery charges. R v Briscoe and Luffman, an alleged contract killing of Luffman’s ex-husband by the hit-man Thomas Convery. Convery having been previously convicted of the murder, he became the Crown’s star witness against those he alleged hired him. R v Reid, an alleged shooting of a police officer whilst in the execution of his duty.

In defamation he acts for both plaintiffs and defendants and regularly gives pre-publication advice to over 20 diverse publications. He has been pro-bono defamation adviser to The Big Issue since its inception.

Kieran Maidment advises film makers, publishers, national galleries and exhibitors on matters of obscenity and indecent display and control. Most notably he advised the Hayward Gallery on the controversial Robert Maplethorpe exhibition, and the Hayward Gallery’s exhibition “Spectacular bodies, the art and science of the human body from Leonardo to now” (which involved the controversial exhibit of a foetus holding a testicle). He appears before the British Board of Film Classification (BBFC) appeals committee arguing against refusal to classify or misclassification. He also advises the Oxford University Press, the Terence Higgins Trust and Sony Games.

He is named as a Leader in the Field (Crime) in the current Chambers and Partners Directory. He is an approved pupil supervisor.