If the Gillard government stares down the nation's media bosses and introduces a public interest test for media ownership that's tough, effective and free from political interference, it will be the first government in the world to do so.

So far, public debate on the proposed test -- a key recommendation of the Convergence Review -- has been heavy on righteous rhetoric but light on facts. Look no further than today's letter from seven media bosses slamming the proposal as a "political interest test" that "has the capacity to be misused by politicians of all persuasions to block the acquisition of media companies by people they do not agree with or simply do not like".