I normally translate unverzüglich as without undue delay. This is always in contracts governed by German law where the German-language version takes precedence.
The background is in section 121 of the German Civil Code, which contains a statutory definition (Legaldefinition):
§ 121 Anfechtungsfrist
(1) Die Anfechtung muss in den Fällen der §§ 119, 120 ohne schuldhaftes Zögern (unverzüglich) erfolgen, nachdem der Anfechtungsberechtigte von dem Anfechtungsgrund Kenntnis erlangt hat. Die einem Abwesenden gegenüber erfolgte Anfechtung gilt als rechtzeitig erfolgt, wenn die Anfechtungserklärung unverzüglich abgesendet worden ist.
Section 121 Period for avoidance
(1) Avoidance must be effected, in the cases set out in sections 119 and 120,without culpable delay (without undue delay) after the person entitled to avoid obtains knowledge of the ground for avoidance. Avoidance made to an absent person is regarded as effected in good time if the declaration of avoidance is forwarded without undue delay.
The translation is a bit odd, but there is no good solution. The German gives the definition first (without culpable delay) and the term defined (unverzüglich) in brackets. The English seems to say that whenever in the text of the Civil Code we encounter without undue delay we should read it to mean without culpable delay. That is the way brackets are used in many statutory definitions in German.
I certainly don’t think that an English-speaking reader would understand ‘without undue delay’ to mean ‘without culpable delay’. But it does indicate that not every delay will be a problem.
Triebel/Vogenauer write that a lot of terms that are precise in German law, and even have a statutory definition as in this case, have English semi-equivalents that are rather vague.
The contracts I translate have usually been governed by German law and with the German version taking priority, my translation just for convenience, and they have usually been for individuals in big companies to understand, but if they have a legal problem, they will consult a German colleague or lawyer because the German version prevails. However, there are many contracts written in English but governed by German law. I would not translate one of those because I’m not a practising and insured lawyer. Triebel/Vogenauer is written with those lawyers in mind. Their knowledge of law may be better than their knowledge of the English they draft it in.
There are two ways of handling this in such a contract: 1) write ‘without undue delay (unverzüglich, §121 BGB)’ or something along those lines 2) attach a glossary to the contract including all the terms with a specific meaning in German that would need explanation in English.
Triebel/Vogenauer (305 ff.) discuss the problem of translating vague English terms in German and using the German term with a statutory definition, for example translating ‘without (undue) delay’ as ‘unverzüglich’ in the sense of section 121 of the Civil Code. They give a table of such terms with both a definition of the English meaning and a partial approximation in German law.
Ken Adams encountered this problem in 2015 – see the post “Shall Without Undue Delay” (Including a German Angle). I was alerted to this article in Twitter only this week.
He thought ‘promptly’ was more elegant than ‘without undue delay’. He received an email from an attorney in Düsseldorf who cautioned against this is the contract was governed by German law. He explained the problem and added ‘So I tend to use “without undue delay”, often followed by “unverzüglich” in brackets’. There are some useful comments thee, including two from Stuart Bugg, who does translate such contracts. (His book, Contracts in English, is ot based on the law of any particular jurisdiction, and it contains an apendix with German translations of legal terms).
On Juraforum there is a list of terms given a Legaldefinition (statutory definition) in German law.
Legaldefinition meint eine im Gesetz enthaltene Definition eines unbestimmten Rechtsbegriffes. Sie sind oftmals daran zu erkennen, dass das definierte Wort nach der Definition in Klammern steht.
Zum Beispiel: Anspruch, § 194 Absatz 1 BGB
„Das Recht, von einem anderen ein Tun oder Unterlassen zu verlangen (Anspruch), unterliegt der Verjährung.“
Ein Anspruch ist gem. der Legaldefinition in § 194 Absatz 1 BGB ein Recht, von einem anderen ein Tun oder Unterlassen zu verlangen.