Case C-517/26, Aranzadi La Ley – when a browser extension rewrites a rival's page
Two of Spain’s largest legal-information publishers are arguing about a browser extension. The Software Directive was written in 1991 and codified in 2009; it has never been asked whether one company may reach into another’s webpage while the reader is looking at it.
Facts
Aranzadi La Ley S.A.U. is suing VLex Networks, S.L. before the Spanish courts. VLex distributes an extension for Google Chrome. When a user with that extension installed visits webpages hosted by Aranzadi — pages offering legal content — the extension temporarily halts browsing and, by adding instructions to the HTML source code of those pages while the original program is executing, opens a modal window on screen. The window offers the reader a choice: stay on Aranzadi’s page, or continue on vLex’s own pages, which offer legal content of their own. VLex retains technical control over the extension and benefits economically from its effects, but the effects are produced only if a user installs it and takes up the option. The Tribunal Supremo (Supreme Court, Spain) has referred three questions.
Questions Referred
According to the Official Journal notice, the Tribunal Supremo asks:
1. Does the concept of ‘alteration’ within the meaning of Article 4(1)(b) of Directive 2009/24/EC include a situation in which a third party, without the consent of the owner of the original computer program (consisting of a number of webpages offering a variety of legal content), offers the user the option of activating an IT application (‘extension’), available on a particular browser (Google Chrome), one of the functions of which is to provide access to the legal information services supplied by that third party, when visiting webpages hosted by the owner of the computer programs, with the result, if the user takes up that option, that browsing on the webpage or webpages hosted by the owner of the original computer program is temporarily halted.
2. Does the temporary modification of the so-called ‘HTML source code’ for the owner’s webpages, by the addition by the third party during the execution of the original program, without consent, of certain instructions which cause to open up on the user’s screen a modal window or dialogue box offering the user the options of remaining on the owner’s webpage or continuing his or her browsing on a webpage owned by the third party (which also offers legal content), constitute in itself an act of alteration which infringes the protection of the computer program within the meaning of Article 4 of Directive 2009/24/EC.
3. Could the third-party owner of the IT tool (an extension over which the owner retains technical control and from the effects of which it benefits economically) rely on the exception provided for in Article 5(1) of Directive 2009/24/EC, on the ground that, in order for its application to produce its effects on the original computer program, the cooperation of a user who has purchased the third-party extension acting on the browser is essential, even if that extension is used not for the purpose intended by the owner of the original computer program but for that intended by the third party.
Sources
OJ notice C/2026/4291 (EUR‑Lex) · Case file on CURIA · Directive 2009/24/EC
Comment
The three questions all assume something the Court may not accept: that the webpages are a computer program. Question 1 says so in a parenthesis — “the original computer program (consisting of a number of webpages offering a variety of legal content)” — and everything downstream depends on it. That parenthesis is the weakest joint in the reference, because the Court has spent fifteen years narrowing what the Software Directive actually protects.
In Case C‑393/09, Bezpečnostní softwarová asociace (ECLI:EU:C:2010:816) it held that a graphic user interface is not a form of expression of a computer program within Article 1(2), and cannot be protected by copyright as a computer program — though it may be protected as a work under Directive 2001/29 if it is its author’s own intellectual creation. In Case C‑406/10, SAS Institute (ECLI:EU:C:2012:259) it added that neither the functionality of a program, nor the programming language, nor the format of data files is a protected form of expression. What is left inside the Software Directive is the code as such. A webpage as the reader encounters it — layout, content, interaction — looks a great deal like the things those two judgments placed outside. Before the Court can say whether adding instructions to HTML is an “alteration”, someone has to identify what the protected program is: the software running on Aranzadi’s servers, which vLex never touches, or the markup delivered to the browser, which on BSA’s logic may not be a computer program at all.
Question 2 has a second difficulty of its own. Article 4(1)(b) reserves to the rightholder the “translation, adaptation, arrangement and any other alteration of a computer program”. The modification here is transient, happens in the user’s browser, and operates on a copy the user lawfully received; Aranzadi’s own files are untouched. Whether the exclusive right reaches a change made downstream on a copy in someone else’s memory, and undone when the tab closes, is a genuinely open question — and answering yes would extend the right well past what “alteration” has previously been understood to reach.
Question 3 is the one where the referring court has already done the analytical work, and it shows. Article 5(1) permits acts necessary for the use of the program by a lawful acquirer in accordance with its intended purpose, and Case C‑13/20, Top System (ECLI:EU:C:2021:811) read that provision generously in the acquirer’s favour — the lawful purchaser may even decompile to correct errors — but bounded it twice over: only “to the extent necessary”, and subject, where applicable, to the contract with the rightholder. Neither bound helps vLex. It is not the lawful acquirer; the user is. And the referring court’s phrasing puts the mismatch beyond doubt: the extension is used “not for the purpose intended by the owner of the original computer program but for that intended by the third party”. An exception drawn around the acquirer’s own legitimate use is an awkward hiding place for a competitor who supplies the tool, keeps technical control of it and takes the economic benefit.
What makes this worth more than its Spanish facts is where an affirmative answer would put a whole category of conduct. Extensions that inject into pages — coupon and price-comparison overlays, content blockers, competitor prompts — have always been fought, when they are fought at all, under unfair competition law, where the claimant must show something about market behaviour. Recast as alteration of a computer program, the same conduct becomes copyright infringement, with the stronger remedies and lower evidential burden that follow. That is a large shift to hang on a browser extension in a dispute between two legal publishers, which is presumably why the Tribunal Supremo declined to decide it alone.