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AT&T Signposts (excluded subject matter: computer-implemented invention))

from here

The AT&T signposts


Although the Aerotel test may involve the examiner checking “whether the actual or alleged contribution is actually technical in nature” - and Symbian actively requires the question “does the invention make a technical contribution” to be asked when considering the computer program exclusion - the judgment in Aerotel/Macrossan does not provide much guidance on how this is to be carried out in practice. However, in paragraph 40 of AT&T Knowledge Ventures/Cvon Innovations v Comptroller General of Patents [2009] EWHC 343 (Pat) (AT&T/CVON), Lewison J (as he then was) set out five signposts that he considered to be helpful when considering whether a computer program makes a relevant technical contribution. In HTC v Apple [2013] EWCA Civ 451, Lewison LJ reconsidered the signposts he had suggested in AT&T/CVON and, in light of the decision in Gemstar-TV Guide International Inc v Virgin Media Ltd [2010] RPC 10 (see 1.37.1 and 1.40.4), felt that the fourth signpost had been expressed too restrictively.


Drawing on the cases identified in Symbian as key to understanding the computer program exclusion, the signposts are a distillation of the reasoning and rationale of this previous case law. (The decisions that each signpost derives from can be found in brackets following each signpost).

The signposts are:-

(i). whether the claimed technical effect has a technical effect on a process which is carried on outside the computer (from Vicom)

(ii). whether the claimed technical effect operates at the level of the architecture of the computer; that is to say whether the effect is produced irrespective of the data being processed or the applications being run (from IBM T 0006/83, IBM T 0115/85, Merrill Lynch, Symbian)

(iii). whether the claimed technical effect results in the computer being made to operate in a new way (from Gale)

(iv). whether the program makes the computer a better computer in the sense of running more efficiently and effectively as a computer (from Vicom, Symbian; as reworded in HTC v Apple)

(v). whether the perceived problem is overcome by the claimed invention as opposed to merely being circumvented (from Hitachi T 0258/03 – note that the problem in question must be a technical problem)


It should be clear that the signposts are merely guidelines; although they provide a useful aid for the examiner in assessing the technical character of a claimed invention, they were not intended to provide a definitive test (as Lewison LJ’s obiter remarks in paragraph 149 of HTC v Apple make clear). Several judgments have emphasised this point - John Baldwin QC (sitting as a Deputy Judge) in Really Virtual Co Ltd v UK Intellectual Property Office [2012] EWHC 1086 (Ch) noted that the signposts, although useful, are no more than signposts and that there will be some cases in which they are more helpful than in others. Kitchin LJ made similar remarks in paragraph 51 of HTC v Apple – their usefulness does not mean they will be determinative in every case. However, if the claimed invention fails all of the signposts, it will likely be a good indicator that it may be nothing more than a computer program as such.

  • [If referring to the AT&T signposts in an examination report, examiners may find it useful to use PROSE clause RC4A.]