This is an interesting story. John Marjoram, Mayor of Stroud, Quaker and Pacifist who I've mentioned before decided not to fill in his Census form. His reason was that an American arms dealer, Lockheed Martin had been awarded the government contract to gather the data. Mr Marjoram didn't like the idea of (indirectly) doing business with them.
Anyway, the matter came up at the Magistrates Court in February and he pleaded "not guilty". They asked him "Why?" and he explained. They were not impressed and told him that his reasons didn't amount to a legal defence. Still, he was set for his "day in court" on 31st May.
Then something odd happened. The Crown Prosecution Service told him that they were dropping the case against him due to a lack of enough evidence ‘to provide a realistic prospect of conviction.’
Now, it would seem to me that there was in fact plenty of evidence. Not only had he not sent in his form, he'd admitted it!
Now, had the CPS persisted, Mr M would have ended up explaining his point of view to a Jury and anyone else who could be bothered to wander down to Bristol Crown Court. The judge would probably have strongly advised the Jury that Mr. M didn't have a leg to stand on.
Juries don't always follow the advice of learned judges. They might have brought in a "not guilty" verdict which would have been embarrassing. Even if the case had ended with a "correct" verdict, Mr M would have got a platform.
That's probably why the CPS withdrew.
Press report of the case
Clive Ponting case has some similarities