In this recent blog post I said that usually in contracts the verb guarantee is followed by a noun rather than a that-clause. But I’m not sure I can explain the aversion to guarantees plus that-clause.
I think it’s safe to say that “Acme guarantees that Widgetco will comply with its obligations under this agreement” conveys the same meaning as “Acme guarantees Widgetco’s compliance with its obligations under this agreement.” In fact, using a that-clause allows you to use a verb rather than an abstract noun, which results in prose that’s clearer and more concise.
Is the issue that guarantees that seems too colloquial?
I agree that “guarantees that” seems better avoided, but I also cannot quite put my finger on it. I have two ideas about it.
Firstly, drafting is generally clearer if the sentence structure reflects how we think about the obligation. As a guarantee is a secondary obligation that relates directly to a primary obligation, it fits more closely with its structure for the object of the guarantee – the primary obligation – to be the direct object of the verb, as a noun phrase. To say “guarantees that” turns “guarantee” into an intransitive verb (I think?), and so, in a grammatical sense, hides the object of the verb. To me, that may explain why the formulation seems too “colloquial” (i.e. imprecise).
Secondly, saying “guarantees that” seems to raise a question about what the consequence of a breach is. If I say “I guarantee that X will perform the services”, it feels more like a representation/warranty rather than a technical guarantee, despite the use of the word “guarantee”. Whether this concern is well-founded in law or not, I couldn’t say (and trawling the cases would only give an indication, as it is a question of contractual interpretation). I would rather avoid the question.