Step 1 : Introduction to the question "What French phrase is also a legal term for a situation outside of human control?"
A tour de force (See here under tour3, sense II.A.1.) is an impressive feat. The word(there are three tour, of differing etymologies) is ultimately from an Old French turn, a noun derived from what became tourner which through an elaborate series of semantic expansions acquired themeaning of "feat, ...
All the more so when you're dealing with the numerous words and phrases that simply don't have an obvious English equivalent. Here's a list of ten of the most common so-called 'untranslatable' French words. The Local has stepped in to provide some handy definitions to help you translate the untranslatable. But what