I assume you are referring to clause 39, but it says "or" indicating a jury trial is not necessary?
> No free man is to be arrested, or imprisoned, or disseised, or outlawed, or exiled, or in any other way ruined, nor will we go against him or send against him, except by the lawful judgment of his peers or by the law of the land.
As to why that is - the explanations I've seen generally feature incompetence amongst various parts of the system and a degree of underfunding (or perhaps poorly managed funding) - including the fact that there is a shortage of criminal barristers due to poor pay. Juries themselves don't seem to be cited as a huge problem.
0. https://www.gov.uk/government/collections/criminal-court-sta...
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