@Graham Marsden
Clearly you don't know much about the law.
I'll make it really simple for you...
Manning allegedly stole classified documents and placed them on Wikileaks.
For the sake of this argument, you can assume his guilt.
Did Manning act alone?
What conversations occur between Wikileaks(their lawyers) and the US Government prior to the release of the flood of documents.
Is there evidence of Assange being complicit in Manning's crime?
Is there enough evidence to show that Assange did commit a crime?
The short answer is that the US Government doesn't know and is in fact investigating and gathering evidence. You do realize that this is something that they do, right? Its the law.
So as they work through the evidence and look at leads and gather more evidence. While you don't know what evidence they have,you can't say that they are 'on a fishing' expedition. As I stated in an earlier post, the I MP made public comments concerning her involvement with Assange therefore opening the door to herself being investigated.
With respect to the Twitter account.
There was enough evidence of the twitter account to have some involvement with Assange's case for a US Judge to sign off on a subpoena. Again as I pointed out in an earlier post, until the US Government gets the information from Twitter, they don't know who owns the account, and who has been using the account. And yes, when one gets a subpoena, they ask for everything and anything that they can think of.
What you fail to miss is the fact that it was the I MP that outed herself in public. Twitter doesn't fight the subpoena, the person who wishes to conceal his/her identity does. So all of this occurs in private. So why did she out herself in public?
Specifically in the law, Twitter is obligated to hand over the information when requested. However they have the right to challenge the Sub and to allow the individual to fight the sub as well. This is actually quite common and its not just the government getting a subpoena. Many companies sue John Doe and then get a subpoena to get the identity of the individual. I was tangentially involved in such a case. (And yes, I've had a government agency subpoena my identity too.) In this case, the individual fought the sub and won. (He shared his identity with the judge in private and showed that he was not the individual that they thought he was.)
So yes, while you whine about the unfair actions of the US Government, please understand what you are talking about. There is an ongoing investigation and when the time comes, the Government will make their case and connect the dots. Jumping to conclusions that the US Government is evil and is the cause of all that is wrong in this world is just absurd.