As reported by Deutsche Welle and many other press outlets, the British government has been roundly criticized for poor translations of a Brexit whitepaper. The German version in particular has been criticized for poor grammar, poor word choice and archaic expressions.
It is unfortunate that the British government failed to employ professional translators for such an important job, but even more unfortunate is what appears to be the root cause: an assumption that skilled language users are capable of translation. As Amy Booth writes for the Independent, the idea that “having an A-level somehow makes you fluent” leads to such “international embarrassment.”
Except in cases where there is a dearth of native speakers, the standard practice is that professional translators do not translate from their A (native) language into their B (second) language. Learning to write well in one’s native language takes years of practice, and it is extremely unusual for anyone not raised with a language to attain such a high capacity. Even if a fluent speaker is able to speak with flawless grammar, writing entails a different set of complex skills that can rarely be mastered by non-natives.
For a discussion on attitudes regarding translation directionality, see the monograph by Nataša Pavlović titled “Directionality in translation and interpreting practice. Report on a questionnaire survey in Croatia.”