Miranda was held under a controversial provision of Britain's Terrorism Act. His detention sparked political and journalistic outrage in several different countries.
The White House said Monday that it had been given a "heads up" about Miranda's imminent detention by British authorities before it happened.
Miranda told the Guardian, which had paid him to travel to Berlin to meet with journalist Laura Poitras, that he was continually threatened with jail time during his detention. He said he was offered a lawyer, but refused one. The interrogators questioned him relentlessly about Greenwald, Poitras and NSA leaker Edward Snowden.
Miranda called it a "total abuse of power."
There has been some controversy about what, exactly, Miranda's role in Greenwald's work is. Amnesty International referred to him as an "employee" of the Guardian, but Miranda said he was merely an intermediary between Poitras and Greenwald.
"It is clear why those took me," he said. "It's because I'm Glenn's partner. Because I went to Berlin. Because Laura lives there. So they think I have a big connection. But I don't have a role. I don't look at documents. I don't even know if it was documents that I was carrying. It could have been for the movie that Laura is working on."
Read the full interview here.