Julian Assange’s next court appearance, on Wednesday, has nothing to do with sex or U.S. diplomatic cables or even with WikiLeaks. But it may make an important contribution to European law. The United Kingdom Supreme Court will be considering the point I raised on his behalf when a Swedish prosecutor claimed to be a “judicial authority” empowered to issue a warrant to have him extradited from Britain to prison in Stockholm. My written argument began quite bluntly: “The notion that a prosecutor is a ‘judicial authority’ is a contradiction in terms.”

The principle is simple, at least in Anglo-American law. Judges must, as their defining quality, be independent of government. Police and prosecutors employed and promoted by the state obviously cannot be perceived as impartial if they are permitted to decide issues on the liberty of individuals. They are expected to be zealous in working up evidence against a suspect, so they are the last people who can be trusted to weigh up impartially the evidence they themselves have drummed up. That is a matter for a court.
So how comes it that in Sweden and 11 other continental countries, prosecutors and even policemen are allowed to issue a European Arrest Warrant (EAW), which has the draconian effect of requiring the arrest of people in another country and dragging them off for trial in the state that has issued the warrant?
The answer partly derives from the lack of principle in the historical development of criminal law in Europe, where for centuries prosecutors and ministers of justice have exercised powers that in the U.K. and U.S. would need judicial approval. That Napoleonic figure, the “investigating magistrate”—a judicial official who conducts a pretrial investigation—has helped to muddy the distinction between law-enforcement agencies and judges.
So when all the major European countries got together 12 years ago to devise a fast track extradition process and decided that EAWs requiring the arrest and surrender of individuals could be issued by “judicial authorities,” there was some confusion about what that term meant, and whether police and prosecutors might qualify. Sweden and some other European countries thought they did, and so one of their prosecutors—not one of their courts—issued the warrant.
It will be inconvenient if Assange’s appeal succeeds, because 12 European countries will have to change their extradition procedures if they want to get their hands on suspects from the U.K. But the argument from inconvenience is the classic way for civil liberties to be lost.
The principle of judicial independence is especially important in the Assange case, where an allegation of what Swedes describe as “minor rape”—another contradiction in terms—was dismissed by a very experienced Stockholm prosecutor. It was later revived, in an unfair process from which Mr. Assange was excluded, by another prosecutor with a gender agenda who was given to issuing self-promoting press statements and withholding exculpatory evidence. Hence the argument that she was an inappropriate personage to take what should have been an impartial decision about whether an EAW should issue against her quarry, in order to interrogate him in Sweden, or whether he should simply be interviewed, as he offered, by video link from London.
The Supreme Court could reject his appeal on the ground that “judicial authority” has a wider meaning in European than in English law. Even a ruling in Assange’s favor would not prevent Sweden from extraditing him eventually, but it would have to change its procedures and then have his EAW issued by a court. The current position, that anyone in the U.K. can be arrested, deported, denied bail, and then tried in secret—the procedure for dealing with sex-crime charges in Sweden—all on the say-so of a prejudiced foreign prosecutor, could strike some judges as oppressive.