Living in self-imposed exile in Russia, former U.S. National Security Agency contractor Edward Snowden may be safely out of reach of the Western powers. But dismayed by the continued airing of trans-Atlantic intelligence, British authorities are taking full aim at a messenger shedding light on his secret files there — the small but mighty Guardian newspaper.

The pressures coming to bear against the Guardian, observers say, are testing the limits of press freedoms in one of the world's most open societies. Although Britain is famously home to a fierce pack of news media outlets — including the tabloid hounds of old Fleet Street — it also has no enshrined constitutional right to free speech.

The Guardian, in fact, has slipped into the single largest crack in the free speech laws that are on the books: the dissemination of state secrets protecting queen and country in the British homeland. The Guardian, along with The Washington Post, was the first to publish reports based on classified data spirited out of the United States by Snowden.