Article 4 of the UK-US extradition treaty
Article 4 stipulates that prisoners cannot be extradited to face politically motivated charges.
In the indictment against Julian Assange, the US government is charging Assange with one count of conspiracy to commit computer intrusion. The charges allude to an incident in 2010 when Assange allegedly helped former US soldier, Chelsea Manning, crack a password stored on a Defense Department (DoD) computer to gain access to a network in which classified documents and communications are stored.
When you look at what he is alleged to have done, he did nothing more than attempt to protect his source (Chelsea Manning). He attempted to break the password to gain access to the DoD computer network so that Chelsea Manning, who was an IT Analyst, could access the information without being traced. This falls under the purview of a journalist protecting the identity of its sources. It is standard practice for journalists to take measures to protect the identity of their sources. There is nothing wrong with taking steps to protect a source's identity, as Assange did.
Journalists are permitted to take steps to protect their source's identity, but these steps must be within the boundaries of the law. Hacking into a government network by cracking a DoD password is not within the boundaries of the law. Therefore, even if Assange was only doing it to protect Manning's identity, it is still a crime. Given Assange knowingly committed a crime and conspired with Manning to hack a government computer network, he should be extradited to the US.
[P1] Journalists take steps to protect a source's identity all the time. This is not illegal. [P2] Therefore, Assange did not commit a crime.
[Rejecting P1] They may take steps to cover their source's identity, but these must be within the boundaries of the law. Hacking a government network is not within those boundaries.