The most recent Irish republican cases to be cited as precedents for English purposes are those of Coughlan (Joseph) and Coughlan (Martin). In the first, both Coughlans had been convicted of conspiracy to cause explosions after the trial judge had directed the jury to acquit both or convict both, applying the common law rule that conspiracy can only be committed by two or more persons. On appeal it was held that this was a correct direction and that no injustice had been done. Second, in Coughlan (Martin), the ground of appeal was autrefois convict – Coughlan had been tried twice for separate sub-conspiracies which might have been part of the same main agreement, and he argued that he had been tried twice for the same offence. Dismissing his appeal, the Court of Appeal stated that the sub-conspiracies could, as a matter of law, be tried separately, and that an accused who pleads autrefois convict must prove that he has already been convicted of the offence with which he is charged. Thus the Irish trials continue to contribute to English law.
The Irish cases help to clear up another problem of analysis in relation to the historical development o conspiracy. This is the fact that, from an examination of Archbold, it appears that there is no chronological consistency in the growth of conspiracy law, but rather two distinct phases of intense judicial activity. Almost two-thirds of the cases currently cited in Archbold date from before 1920: the great majority of the remainder were decided after 1960. In an Irish context, the reasons for this are clear. By 1920, English courts had effectively ceased to have jurisdiction over Ireland, and one can hardly expect the Law Reports to be full of Irish cases. The second great phase of development started in the 1960s with DPP v Shaw, climbing to a peak of prosecutorial obsession in the 1970s, in parallel with the Ulster crisis.
As Boyle, Hadden and Hillyard comment:
In all cases…the main focus of the legal system is likely to change when the existing state is threatened either by external attack or internal subversion. In these new and usually temporary circumstances the legal system is likely to be openly used by those in power to suppress internal opposition, more or less regardless of the values which the legal system is thought to embody in more stable times.
We might comment that in Ireland, so far as conspiracy law is concerned, these ‘temporary circumstances’ have lasted for at least two centuries.