He conducted the inquiry into the Timothy Evans/John Christie murder miscarriage of justice case, which was conducted over the winter of 1965–66. Timothy Evans had been hanged in 1950 for the murder of his small child, Geraldine, after a trial in which his then landlord, John Christie, testified against him. Three years later Christie was found guilty of multiple murder of women in his house, 10 Rillington Place, and he himself was tried for murder, found guilty and hanged. Before he died, he admitted to killing Beryl Evans, and so it was likely that Timothy Evans had been innocent, and had been hanged wrongfully. Brabin found it was "more probable than not" that Evans murdered his wife and that he did not murder his daughter. This was contrary to the prosecution case in Evans's trial, which held that both murders had been committed by the same person as a single transaction. The victims' bodies had been found together in the same location and had been murdered in the same way by strangulation. Despite his perverse conclusion, the Brabin enquiry exposed police malpractice during the Evans case, such as destruction of evidence. The neck tie which had been used to strangle Geraldine, for example, was destroyed by the police prior to the discovery of Christie's crimes in 1953. Even the record book in which the destruction had to be noted, was itself destroyed by the police. In most serious cases, police are required to preserve all material and documentary evidence, so the removal of evidence in this case is suspicious. Many police statements were contradictory and confused as to dates and times of interviews with key witnesses, especially of the Christies during the first murder case. Brabin went to great lengths to prefer police evidence wherever possible, and exonerate them of any police misconduct, and he didn't address the allegations made by Ludovic Kennedy about the validity of several of the confessions allegedly made by Evans. He never considered the incompetence of the police in their searches of the garden at 10 Rillington Place, and had a poor understanding of the importance of forensic evidence. The enquiry did little to settle the many issues which arose from the case, but, by exonerating Evans of killing his child, was crucial in subsequent events. Since Evans had only been convicted of the murder of his daughter, Roy Jenkins, Soskice's successor as Home Secretary, recommended a royal pardon for Evans, which was granted in October 1966. In 1965 Evans' remains were exhumed from Pentonville Prison and reburied in St Patrick's Roman Catholic Cemetery in Leytonstone, Greater London. The outcry over the Evans case contributed to the suspension and then abolition of capital punishment in the United Kingdom.
Brabin ruled in the case R v Commissioner of Metropolitan Police, ex parte Blackburn on the duty of the Crown to prosecute. The case was described as follows: "A and B are alleged to have committed a crime. A is charged with the crime, convicted and sentenced. B is not charged. At the trial of A there is evidence which suggests that B may have committed or been a participant to the crime. Can the prosecution be compelled to prosecute B?" In 1968, the Court of Queen's Bench of Widgery CJ, Melford Stevenson and Brabin issued judgment that "to prosecute must indisputably be a matter of discretion", and that "No minister of the Crown can tell that he must, or must not, keep observation on this place or that; or that he must, or must not, prosecute this man or that one. Nor can any police authority tell him so. The responsibility for law enforcement lies on him. He is answerable to the law and to the law alone." In 1972, this judgment later was affirmed, in a separate judgment against Blackburn for another matter, by the Court of Appeal. The original Blackburn case in 1968 dealt with Blackburn's allegations of a London illegal gambling establishment, whereas in Autumn 1972 he brought an action for mandamus for failure to arrest on pornography laws, which later was adjudicated in the Court of Appeal. The case was noted as recently as the 1998 decision of the Lords Regina v. Chief Constable of Sussex Ex Parte International Trader's Ferry Limited 1998 UKHL 40, concerning police protection for the customers of ITF, a company involved in the export of livestock through the port of Shoreham, during the early months of 1995 when animal rights protesters were trying to stop the trade.
