My understanding is that all quotes must be delimited by double quotes, and that a quote must be exactly what was said. This raises the problem of how to handle quotes made in a foreign language.
My assumption is that a translated quote is never placed inside double quotes. All translations are interpretations, not what was actually written / spoken. So, is this a big deal? yes. When translating into one's native language, you can easily spin a translation to make it seem like it has meaning that is not really there. And then, by delimiting it with double quotes, you can make it look like that poisoned quote is exactly what a non-native speaker said. Readers don't stop to think about the possible agenda of the translator.
These days, I've started reading the news. And, I am seeing a lot of quotes in doubles quotes assigned to people who I assume cannot speak English at an advanced level.
When I read an article in The Economist, The New York Times, etc. and I see a quote, in double quotes, attributed to a foreign leader, was the leader speaking English, or is that double quoted quote really a translation? In my own translation work, might it actually be better to use double quotes to delimit translated quotes because that is the expected standard?