— 6 — it contained and the files which had been downloaded onto the Customs Officer’s computer. Postings and e-mails from “Big Crook” were also retrieved from the newsgroup’s server. 16. On the basis of his analysis, the forensic expert concluded that the appellant’s computer was the original source (or, in BitTorrent parlance, the initial “seeder” computer) from which copies of the films had been downloaded by the Customs Officer (and others), prompting the bringing of the charges. 17. To resolve the issues raised by the appellant, it is necessary to undertake a more detailed examination of how BitTorrent technology operates and how it was applied in the present case. D. 18. BitTorrent technology as applied in the present case The technical evidence was not disputed and was accepted by the magistrate. It may be summarised as follows. 19. A motion picture, when reduced to digital form, represents a very large quantity of data. If it were sought to make such a film available using traditional client-server technology whereby all those wishing to download the film would have to gain access to it from a centralised server, a serious bottleneck would be likely to occur in the flow of data, making the downloading process so slow as to be impracticable. 20. The BitTorrent system, which is a variant of what is known as a “peer-to-peer” file sharing system, avoids such a bottleneck. It does not involve a centralised computer but is designed so that individual computers “share” the material they have downloaded from a source by re-transmitting it to other “peer” computers. The BitTorrent system requires there to be a computer which acts as the initial “seeder”, that is, the original source of the files to be downloaded. It also requires a different computer to act as a “tracker