Sure, some of English is based on French, and there are a few words taken unmodified. But when it comes to legal terms, Norman French was used by lawyers in English-speaking countries for centuries. As a result, ideas and terms from French law are just taken wholesale by English-speaking legal systems (including grammar and syntax very foreign to English). http://en.wikipedia.org/wiki/Law_French#Survivals_in_modern_...
'S what I just said. From your link: "It [French] was used in the law courts of England, beginning with the Norman Conquest." If the average person habitually used legal terminology the way they use words like, say, "toilet," the Frenchness of those words would be completely inconspicuous.
Besides, it was French that shamelessly ripped off Vulgar Latin (re + portare, "to carry back")!