|Et tu, Brute? ("La Morte di Cesare", by Vincenzo Camuccini)|
According to General Advocate Trstenjak, there can be no doubt that "Et tu, Brute?" is a reproduction in part of William Shakespeare's play "Julius Caesar". Alas, it was definitely not Shakespeare who first penned the phrase in question (see Marjorie Garber, Shakespeare's Ghost Writers: Literature as Uncanny Causality, 55-56). Apparently it was in common use a considerable time before Shakespeare wrote "Julius Caesar".
In addition, there is the question whether three words (or an individual word) may indeed constitute a literary work or a substantial part of a literary work with the consequence that unauthorised reproduction will amount to infringement. In most cases, the answer would appear to be "no", see eg Exxon Corp v Exxon Insurance Consultants International Ltd  Ch 119; Francis, Day and Hunter, Ltd v 20th Century Fox Corp, Ltd  AC 112 ("The Man Who Broke The Bank At Monte Carlo"). Trade mark law, unfair competition law or title protection law is more suited to protecting short slogans or invented words than copyright law. Occasionally, though, the question will be answered in the affirmative. For instance, French courts held that the titles "Les hauts de Hurlevent" (as a translation for "Wuthering Heights", Tribunal commerce Seine, 26 June 1951), "Clochemerle" (invented word combining "bell" with "blackbird", Cour d’appel Lyon, 5 July 1979) and "Vol de nuit" ("Night Flight", Tribunal de Grande Instance de Nanterre, 28 April 1998) were sufficiently original to attract copyright protection.
Nevertheless, even in the latter cases, comprehensive copyright protection might still be excessive. There are two reasons for that. The first concerns proof of authorship, the second that which Neil so fittingly refers to as "genericity".
In respect of the first reason, both General Advocate Trstenjak's example of "Et tu, Brute?" and Neil's example of the "Faustian bargain" illustrate one of the dangers of granting protection to short phrases, slogans, etc.: Shakespeare wrote the play "Julius Caesar", but he did not come up with the phrase "Et tu, Brute?"; Goethe wrote the play "Faust" (and "Faust II", actually), but Goethe neither invented the character of Dr. Faust nor the idea of striking a pact with the devil - that's folklore, and authors such as Christopher Marlowe reworked the Dr Faustus story long before Goethe's time.
No one can tell who first came up with the expression "Et tu, Brute?". Even if it were possible to prove that a certain author first used it in a published literary work, that does not necessarily mean that the phrase originates from that author. Maybe the author picked it up from a historically inaccurate Latin teacher.There are also many instances where two authors will independently come up with the same or a strikingly similar phrase. If the prima facie presumption of authorship (see Article 15 (1) RBC) and the procedural assumption of "subconscious copying" come together in such cases, there is little chance of escaping an unjustified copyright infringement claim.
The second reason refers to cases where the phrase is sufficiently original to render an independent identical creation by someone else improbable, such as Neil's example of the "Catch-22" situation. Yet copyright protection can be excessive precisely because the work has been extraordinarily successful. If the expression in question captures the public imagination and succinctly describes a certain mood, situation, etc, the public will add it to the general store of linguistic expressions, and in such instances freedom of expression will require the phrase to be freely available for all. In that respect, the situation is indeed comparable to the situation in trade mark law, where a trade mark becomes generic and loses its protection if it becomes so successful that it is used by the general public to denote the class of goods or services rather than the particular brand.
One should also be wary of seemingly original phrases such as "Toto, I don't think we're in Kansas anymore" (another example provided by Neil). In a different context, say an account of a car trip from Kansas City to Denver, the remark of one character to another that "I don't think we're in Kansas anymore" would take on a completely different (and rather mundane) meaning.
As always, any comments and views on this topic will be gratefully received!