You dont have to be much of a detective to work out who was downloading that porn
Yes you do. The computer was not forensically examined so every one of those statements could be wrong. Remember that the officer making these allegations originally stated that he had no evidence as to who downloaded the porn and no way of knowing whether or not it was Green.
Green wasn't a passive recipient of a leak
Agreed. I'm not saying his actions with Galley were justified. But it is still true that his actions were on a totally different scale to the behaviour of the ex-police officers in this case.
And if Tories get away with such organised dirty tricks, then Labour will probably follow
If that is a reference to Green/Galley, both major parties have been doing it for a long time. The press have also organised similar leaks against governments of all colours.
A public interest defence is legally a legitimate one to offer, hard to exclude unless the trial is just a gixed sham
A public interest defence has to be relevant. Is there a public interest in knowing that an unidentified person in Green's office had viewed legal porn on a work PC? The answer to that is clearly no. It may be interesting to the public but it is not in the public interest. We know that attempts are made to access porn from PCs inside parliament roughly 700 times a day. This has not added anything significant to our knowledge.
Even if the answer was yes, the revelation is in the public interest, it does not mean details of the porn can be introduced. The jury does not need to know details of the porn to make a decision.
That lawyer will also bring in Green and are entitled to attack his credibly
The lawyer would be a complete idiot to do so. Green is not making any allegations in the case. If the defence called him he would be a hostile witness - defences prefer to avoid those if possible. If the prosecution called him (possible) the defence might bring that up but his evidence will be peripheral to the case (if it happens). The central issue is that a police officer has retained a notebook that he was ordered to destroy, it remains in his possession despite the fact he is no longer a police officer and he has revealed confidential information about non-criminal behaviour. The primary witnesses would come from the Met, not from Green.
Looking at past cases, juries have refused to convict whistleblowers where they feel politicians have acted badly
Occasionally. But this isn't a whistleblowing case. If Green had not denied the initial report of porn being found on a PC in his office he would still be in office. The police in this case have not revealed any criminal behaviour. They have acted as arbiters of society's morals.