Escitalopram (HR, 12/00888, 2013)

Dhenne Avocats · 11 October 2026

Our analysis

Summary

The Supreme Court of the Netherlands (Hoge Raad) set aside the judgment of The Hague Court of Appeal of 24 January 2012, which had invalidated the Dutch part of European patent EP 0 347 066 in respect of its product claims to escitalopram, and remitted the case (para 8). It held that a substance whose composition and possible properties are known may nonetheless involve an inventive step where no process for obtaining it was known in the prior art at the priority date and the claimed process makes it available for the first time in an inventive way; a product patent may then be obtained (para 4.3). The burden of proving lack of inventive step, including the existence of a known process for obtaining the substance, lies on the party seeking invalidation (para 4.5.2). The judgment matters for disputes over enantiomers and other known but previously unobtainable substances.

Facts and procedure

The patentee, whose name is anonymised in the published text, has marketed Cipramil (citalopram) since 1989 and Cipralex (escitalopram) since 2002, both antidepressants (para 3.1(ii)). Citalopram is a racemate of two enantiomers; escitalopram is its (+) or S enantiomer (para 3.1(iii)). EP 066, granted in 1995 without opposition, claims escitalopram and its salts (claims 1 to 5), a preparation process (claim 6) and an intermediate (claim 7) (para 3.1(iv) and (v)). A supplementary protection certificate (SPC) for escitalopram was granted in 2004 (para 3.1(v)). Two generic manufacturers, one of them Centrafarm, sought invalidation of EP 066 and, in the alternative, a declaration that the SPC was invalid (para 3.2). The Court of Appeal invalidated claims 1 to 5, holding that an inventive process alone did not justify absolute protection for the substance (para 4.1(c) and (d)), and, relying on EPO decision T 595/90, placed on the patentee the burden of proving that no process for obtaining it was known (para 4.1(e)).

The applicable law

Inventive step is assessed under Article 56 EPC and Section 6 of the Dutch Patents Act 1995 (ROW 1995), and novelty under Article 54(1) EPC and Section 4 ROW 1995 (paras 4.3 and 5.2.2). The burden of proof follows the general rule in Article 150 of the Dutch Code of Civil Procedure (Rv) (para 4.5.2). The SPC is governed by Regulation (EC) No 469/2009, a product meaning the active ingredient (Article 1(b)) and a prior certificate for the same product rendering the SPC invalid (Articles 3(c) and 15) (para 5.5.1).

Question

Can a substance whose composition and possible properties were known, but which no known process could produce at the priority date, be protected by a product patent, and who bears the burden of proving that a process for obtaining it was known?

Decision

The principal ground of appeal succeeded. The Hoge Raad aligned itself with the settled case law of the EPO Boards of Appeal and with the decisions on the same patent of the German Federal Court of Justice (Xa ZR 130/07) and the House of Lords ([2009] UKHL 12) (para 4.3). The Court of Appeal could not find a lack of inventive step without considering that basis (para 4.4), nor reject the patentee’s case for want of a specific offer of evidence without finding that the generics’ report sufficiently challenged it (para 4.5.1). T 595/90, which concerned grant and a purification case, does not require a different allocation of the burden of proof (para 4.5.2). On the cross-appeal, novelty was upheld: a substance is new if it was not previously available (para 5.2.2). A court is not bound to apply the problem and solution approach (para 5.4.2). Escitalopram is a different product from citalopram under Regulation No 469/2009 (para 5.5.2), but the Court of Appeal should have ruled on the claim for invalidity of the SPC once it invalidated claims 1 to 5 (para 5.6). Additional complaints filed by the patentee after the appeal deadline were disregarded (paras 6.2 and 6.3).

Key points for practice

• The novelty of an enantiomer turns on prior availability: an enantiomer not previously available in pure form is new even if the racemate was known (para 5.2.2).
• A substance whose structure and properties were foreseeable may still be inventive if no known process could produce it and the claimed process does so inventively (para 4.3).
• Practical point: a generic challenger attacking an enantiomer patent must prove with specific evidence that a route to the compound was known at the priority date; in cassation, conditional complaints must be raised in the initial pleading, as late complaints are disregarded (paras 4.5.2 and 6.2).

Provisions applied

European Patent Convention

Art. 54; Art. 56

Regulation (EC) No 469/2009 (SPC)

Arts 1, 3 and 15

National law

Sections 4 and 6 ROW 1995; Articles 150, 407, 410, 426a and 427 Rv

Case law cited

EPO, T 296/87; EPO, T 595/90; BGH, 10 September 2009, Xa ZR 130/07; House of Lords, [2009] UKHL 12; ECJ, 4 May 2006, C-431/04 (MIT); ECJ, 17 April 2007, C-202/05 (Yissum)

Prepared by Dhenne Avocats from the text of the decision (rechtspraak.nl, Dutch text), consulted on 11 October 2026. Only the official text is authoritative.