Criminal cases in England and Wales always start in a magistrate's court. The judge in this case, Vanessa Baraitser, is listed [1] as a "District judge (magistrates’ courts)" - despite the article describing her as "Magistrate Baraitser". District Judges are full-time members of the judiciary, even though they sit in a magistrate's court [2].
Obviously, the case will be considered by other judges on appeal.
Also, extradition proceedings don't follow standard criminal procedure.
See s77(1) of the Extradition Act 2003...
> In England and Wales, at the extradition hearing the appropriate judge has the same powers (as nearly as may be) as a magistrates' court would have if the proceedings were the summary trial of an information against the person whose extradition is requested.
(A summary trial is a trial for a low-level offence - in the US, the equivalent would be a misdemenor. "An information" is a slightly quaint wording for what is basically equivalent to an indictment, except it isn't an indictment because a summary offence isn't indictable.)
In the magistrates' court, you either have a bench of three lay magistrates, or a district judge. More serious issues, including almost all but the least contentious extradition hearings, are likely to be heard by a DJ rather than a lay bench, since a DJ has worked in legal practice in a way a lay magistrate hasn't.
It's being heard at Westminster Magistrate's Court because that is where all extradition cases from England and Wales are heard.
Criminal matters in the Magistrate's Court are heard before Justices of the Peace, and you are correct that most JPs are lay-people who have taken some basic legal training, and are assisted by a clerk who is legally trained at a professional level.
However, there are also District Judges that sit in the Magistrate's Court and are by virtue of their appointment also Justices of the Peace. These are judges employed by the Government to deal with specific types of more serious cases, e.g. terrorism, or specific subject matter like extradition.
I looked this up previously, but it's hard to find useful references due to the preponderance of Assange-related stories, but if I recall correctly: Vanessa Baraitser is a District Judge, and has something like 15+ years of professional experience as a solicitor before appointment.
Extradition cases are the responsibility of the magistrates' courts. In practice, they're not given to benches of volunteer magistrates, but to the group of District Judge (Magistrates Court)s who sit in a single court (Westminster Magistrates Court) and who have experience of extradition work.
DJ (MC)s are professional judges, with the usual legal training, who can sit singly in place of benches of lay magistrates for all the usual work of the magistrates' courts (which is mostly minor crime, straightforward family business, and regulatory civil hearings such as approving liability orders for outstanding council tax). For quite a lot of contentious extradition hearings you actually get the Chief Magistrate, who is a senior district judge.
It does have to be said that not being extradited on the basis of a well-formed request is rare, whether you're Julian Assange or not. If the court is confident that you're accused of an extradition offence, and that your trial will be fair, there are few reasons for it not to extradite (normally these days because of anticipated breaches of the Human Rights Act).
Magistrates' courts are where criminal cases are first dealt with in English law. If the offence is indictable then the next step will be to move the case to the crown court (unless the offence is an "either way" offence and the summary procedure is elected instead).
So it would make sense to me that extradition hearings are dealt with, in the first instance, by a magistrates' court; after all the court is not actually determining guilt, but merely whether there's a prima facie evidence of guilt.
There are procedural safeguards in place, namely that one may appeal to the High Court (and then, ultimately, the Supreme Court) if the magistrate's court send the case to the Secretary of State for approval and the latter approves the extradition.
Tfa is by Craig Murray whereas the edit history of the wikispooks piece [0] at least claims to be by Patrick Haseldine. What makes you say to the contrary?
(For those who don't know, in the UK a magistrate is just a layperson volunteer, not a legally trained judge)