1 Co-offenders Before the Court: The Joinder Effect in Victoria, 1861–1961 Alana Piper and Lauren Vogel It is well established in legal and psychological research that combining multiple charges against a defendant into a single trial event has a tendency to increase the chance of conviction — this is known as the joinder effect. Legal scholars have long theorised that combining the trials of multiple defendants has a similar effect, disadvantaging co-accused by tainting them with guilt by association. However, little empirical evidence has been presented to support this. It has further been suggested that the joinder of co-accused defendants became more pronounced during the twentieth century, as judges in common law jurisdictions became increasingly reluctant to increase the courts’ workload by severing trials. Drawing on a sample of prosecutions data from Victoria, this article explores the impact that being co-accused had on trial outcomes and the wider legal and sociohistorical issues surrounding such joint trials. Keywords: multidefendant trials, codefendants, accomplice evidence, lawyers, criminal procedure Co-accused defendants face a special set of circumstances at trial. In the novel Great Expectations, Charles Dickens depicts some of co-offending’s perils as part of the convict Magwitch’s backstory. Magwitch is prosecuted for a banknote forgery scheme that he has fallen into at the urging of Compeyson, a fraudster from a more gentlemanly background. At trial, Compeyson’s defence strategy is to scapegoat Magwitch as the instigator of the crime. His lawyer draws attention to the differences between them: My lord and gentleman, here you has afore you, side by side, two persons as your eyes can separate wide; one, the younger, well brought up, who will be spoke to as such; one, the older, ill brought up, who will be spoke to as such; one, the younger, seldom if ever seen in these here transactions, and only suspected; t’other, the elder, always seen in ‘em and always with his guilt brought home. Can you doubt, if there is but one in it, which is the one, and if there is two in it, which is much the worst one? 1 Both men are ultimately convicted, but Magwitch’s sentence is twice as long, resulting in his transportation to Australia. Legal scholars in common law jurisdictions have questioned the fairness of joint trials on defendants by pointing out myriad ways that such proceedings benefit prosecutors, including: creating an impression of guilt by association against defendants otherwise less implicated in the crime; increasing the overall complexity of the case and overwhelming the jury’s ability to distinguish the evidence against each individual accused; creating circumstances where evidence that would otherwise be excluded is admitted; encouraging codefendants to implicate each other as part of their defence strategy or in exchange for prosecutorial leniency; and increasing the overall perception of the seriousness of the crime. 2 In an article on joint trials in Australia, Mark Weinberg thus declares that, ‘It is fair 1 Charles Dickens, Great Expectations (Oxford: Oxford University Press, 2008), 321. 2 J. A. Andrews, ‘Joint Trials,’ The Modern Law Review 30 (1967): 645-58; I. R. Scott, ‘Criminal Procedure: A Comparative Note on Joint Trials,’ The International and Comparative Law Quarterly 19 (1970): 585-98; Robert O. Dawson, ‘Joint Trials of Defendants in Criminal Cases: An Analysis of Efficiencies and Prejudices,’ Michigan Law Review, 77 (1979): 1379-455; Don Just, ‘Joinder of Trial of Accused Persons and Its Resistance,’ Law Institute Journal 62 (1988): 948-50; Mark Weinberg, ‘Joint Trials – the Problem of Reciprocal Blame,’ Criminal Law Journal 8 (1984): 197-216; Martin D. Litt, ‘Commentary by Co-Defendant's Counsel on