You're the prime minister of Australia. (Well, you're not, actually, but this is my little rhetorical way of plunging you imaginatively in medias res. I want you to imagine that you're the prime minister of Australia.) Your foreign minister is a former prime minister that you ousted from the leadership in 2010, and now a bitter rival who looks like he's plotting to get back the leadership. You haven't been exactly assiduous in publicly rebutting criticisms of him emanating from your wing of the party, because frankly you wouldn't piss on him if he caught fire. He suddenly decides, while on a trip overseas representing the country, that he's had enough of the insults and attacks, and it's time to make his play. So he resigns his ministerial post and announces his resignation to a press conference at 1:30 a.m. in Washington DC so as to catch the 6 p.m. news in Australia.
Your mission, should you decide to accept it: to say something prime-ministerial about his accomplishments in office without giving one iota of extra support to his candidacy now that he's quite clearly going to come back to Oz and challenge you for your job. What do you say? You don't want to say that he achieved anything, yet you have to uphold the foreign policy record of your government. Is it time for the passive construction?
Here's what Julia Gillard (who, unlike you, actually is the prime minister of Australia, and has been facing approximately the scenario outlined above) chose to say about the service of her treacherous foreign-policy lieutenant Kevin Rudd, who resigned in Washington earlier this week after a series of personal attacks on him by other politicians:
During his period of service as Foreign Minister there were many achievements.
Passive-aggressive, maybe, but not a passive — though it is exactly the sort of utterance that so many commentators have wrongly called a passive (often because the disgrace of Strunk and White's page 18 has confused them, but not always, because other grammar advice sources make the same blunder). The verb achieve is the one that you don't want him to get to be the subject of, so you nominalize it, forming the noun achievement, and pop the result into a bare existential clause, asserting that the achievements exist, but you don't (in that clause, anyway) give him any credit for them.
Grammar lesson: never confuse obfuscation of agency with use of the passive voice. English has all sorts of ways of talking about actions without mentioning who undertook them. Sometimes they are quite legitimately used, and sometimes culpable muddying of the waters is going on — it varies from case to case. But passive voice is not the same as concealing who did what. Neither is necessary or sufficient for the other. [Parenthetical update: John Lawler let me know about a recent remark about Gillard in a different context, here, that mentions the passive accurately for once: "Rudd had sabotaged her from the beginning, Gillard said (neatly described in the passive voice, mind): 'The 2010 election was sabotaged'." That genuinely is a case of using the passive to avoid mentioning Rudd as the saboteur.]
One other thing, to be fair to Julia Gillard. (Long ago some pompous twit accused her of being too stupid to know subject from object, and Language Log defended her here: the pompous twit was completely wrong.) Gillard's full statement on the Rudd resignation, reproduced here on the independent news source Crikey.com.au, follows up "there were many achievements" by saying in the next sentence, "He strongly pursued Australia's interests in the world." That's a straightforward active transitive with the anaphoric pronoun he (referring to Rudd) as the subject. So in fact, if you read on, Gillard was not even being particularly passive-aggressive, let alone aggressive with the passive. She asserted that he had done his job. Anything less wouldn't be prime-ministerial.
And she has a fight on her hands now to make sure she holds on to that position. It's going to be ugly. Ultimately, I'm sure, there will be passives.
[Update, February 27: Whether it got ugly or not, Julia Gillard totally kicked butt in her party's leadership ballot, and is still (unlike you) the prime minister of Australia. Kevin Rudd graciously (for now) accepted defeat. Show's over folks, move along now, nothing to see here.]
[Thanks to Martin Pool for the tip-off. There has been no opening of comments.]