I would also say that this case also considers a different question (in addition to the copyrightability of functionality), of whether observing inputs/outputs is (for legal purposes) decompilation [see also #44 of the ruling, quoted below].
On those grounds, the Court (Grand Chamber) hereby rules:
2. Article 5(3) of Directive 91/250 must be interpreted as meaning that a person who has obtained a copy of a computer program under a licence is entitled, without the authorisation of the owner of the copyright, to observe, study or test the functioning of that program so as to determine the ideas and principles which underlie any element of the program, in the case where that person carries out acts covered by that licence and acts of loading and running necessary for the use of the computer program, and on condition that that person does not infringe the exclusive rights of the owner of the copyright in that program.
The press release itself already notes (see #43 of the decision, below) the important fact that WPL had no access to source code [which is a notable distinction from Rybka/Fruit]:
In the present case, it is apparent from the explanations of the national court that WPL did not have access to the source code of SAS Institute’s program and did not carry out any decompilation of the object code of that program. It was only by means of observing, studying and testing the behaviour of SAS Institute’s program that WPL reproduced the functionality of that program by using the same programming language and the same format of data files. [...] In addition, according to the Court, there is no copyright infringement where, as in the present case, the lawful acquirer of the licence did not have access to the source code of the computer program but merely studied, observed and tested that program in order to reproduce its functionality in a second program.
At any rate, here are some points regarding the copyright question. From the same press release link (see #30, 31, 35 of the decision, I think):
The Court recalls, first, that the Directive on the legal protection of computer programs extends copyright protection to the expression in any form of an intellectual creation of the author of a computer program. For Rybka/Fruit, it seems to me the main contention is what ideas/principles (and "element") means in #30-31:
[...] computer programs are protected by copyright as literary works within the meaning of the Berne Convention [...] that protection [extends] to the expression in any form of a computer program [...] That provision states, however, that the ideas and principles which underlie any element of a computer program [...] are not protected by copyright under that directive.
Are the evaluation features (say) to be construed as elements themselves, or are they the idea that underlies the elements? So I think it relates right back to the idea/expression inquiry. Related to "any form" in the above quotation (from the first part of #31), there is also in #35:
the object of the protection conferred by that directive is the expression in any form of a computer program, such as the source code and the object code, which permits reproduction in different computer languages. This last clause ("permits reproduction") is a bit obscure to me, but in this regard, see also #36-37 below, where preparatory design is included in the term 'computer program'.
From the decision (
linked from the press release):
26. The High Court also points out that two previous courts have held, in the context of separate proceedings, that it is not an infringement of the copyright in the source code of a computer program for a competitor of the copyright owner to study how the program functions and then to write its own program to emulate that functionality.
[...]
36. In accordance with the second phrase of the seventh recital in the preamble to Directive 91/250, the term ‘computer program’ also includes preparatory design work leading to the development of a computer program, provided that the nature of the preparatory work is such that a computer program can result from it at a later stage.
37. Thus, the object of protection under Directive 91/250 includes the forms of expression of a computer program and the preparatory design work capable of leading, respectively, to the reproduction or the subsequent creation of such a program
[...]
41. Moreover, [...] the main advantage of protecting computer programs by copyright is that such protection covers only the individual expression of the work and thus leaves other authors the desired latitude to create similar or even identical programs provided that they refrain from copying.
[...]
43. In that context, it should be made clear that, if a third party were to procure the part of the source code or the object code relating to the programming language or to the format of data files used in a computer program, and if that party were to create, with the aid of that code, similar elements in its own computer program, that conduct would be liable to constitute partial reproduction within the meaning of Article 4(a) of Directive 91/250.
44. As is, however, apparent from the order for reference, WPL did not have access to the source code of SAS Institute’s program and did not carry out any decompilation of the object code of that program. By means of observing, studying and testing the behaviour of SAS Institute’s program, WPL reproduced the functionality of that program by using the same programming language and the same format of data files.
I don't know how one interprets "to create, with the aid of that code, similar elements in its own computer program" in #43 (again with the word "elements"), but it seems to be the crux of the matter. As noted in #44, there was no such code examination in WPL/SAS (only observation of functionality at the level of inputs/outputs), so the question was moot (see #26). With Rybka/Fruit, the question is whether something like evaluation features would be "similar elements" or not in relation to #43 [note that #43 is rather case-specific in its language, involving formats of data files], and exactly what "copying" means in #41.