Essentially Sir Walter was caught up by the Main Plot which conspired to kill James and his children and replace them with Arbella Stuart having been financed by the Spanish and the Hapsburgs. Much of the evidence against Raleigh was based on Lord Cobham’s evidence.
The King’s Sergeant when introducing the case announced that Cobham revered Raleigh and that the former was a simple untravelled man whilst Raleigh was much more worldly.
Raleigh defended himself ably and with humour noting that the entire content of his trial was based on hearsay by one man and that man had received a letter from his wife telling him to pin it on Raleigh. He went on to say that under a law dating from the reign of Edward III that two men were required to condemn a man. Coke, objected saying that horse thieves used that stratagem to avoid condemnation and that to argue against the king’s court on a point of law suggested treasonable intent in itself.
He continued to observe that he was not charged with the Bye Plot which was to kidnap James I – and that if he was part of the conspiracy why hadn’t he been trusted to take part in that particular hare-brained scheme.
Raleigh also made the very good point that the Spanish had never been his friends and that they didn’t look particularly kindly upon him in any event so to accuse him of being in cahoots with the Spanish verged upon the absurd. He continued in that particular vein picking holes in the evidence and observing that he had thought that Lord Cobham was offering him a pension to work for peace- something that Cecil himself had accepted- so it was hardly treasonous.
Looking at the trial transcripts it is clear that under today’s laws the case would have been thrown out. Somewhat ironically James and Cecil needed Raleigh out of the way so that they could make peace with the Spanish.