Live long and copyright many things. Thus Paramount Pictures hopes to prosper as it wages a legal battle with the makers of popular Kickstarter crowdfunded Star Trek fan film Prelude to Axanar. Paramount claims the film's use of the fictional language Klingon adds up to copyright infringement; the filmmakers contend that attempting to copyright Klingon is absurd given the language is an "idea or a system." For legal precedent, they cite the system of bookkeeping: "Although copyright protects the author’s expression of the system, it does not prevent others from using the system." But there's doesn't appear to be a quick and easy answer. The US Copyright Office doesn't specifically "deal with the copyrightability of constructed or fictional languages, let alone Klingon," observes Consumerist, which was unable to dig up much in the way of case law on the matter.
Paramount, which claims exclusive ownership over many Star Trek features, including characters, themes, plots, dialogue, settings, props, character makeup, costumes, sets, fictional language, and so forth, has responded to the filmmakers' plea by noting that "a language is only useful if it can be used to communicate with people, and there are no Klingons with whom to communicate," reports TorrentFreak. By allowing the characters in Prelude to speak Klingon, they assert, the film is infringing on Paramount's characters because speaking the language "is an aspect of their characters." The jury's still out, but Boing Boing goes so far as to call this Paramount's attempt to "kill" the film, and it frames Paramount's claims as "dubious," in part because it borrows phonemes (from Hindi, Arabic, etc.) as well as grammar (from Japanese, Turkish, etc.)—not to mention it's spoken by many fans around the world. (Here's one wild use of Klingon in the real world.)