16 October 2013Biotechnology

Courting controversy: the implications of Brüstle

Embryonic tissue is currently the only source of totipotent stem cells (stem cells capable of differentiating into any other cell type of the body).

Hence, the finding in Court of Justice of the European Union (CJEU) decision C-34/10 (commonly referred to as the Brüstle decision) that inventions are excluded from patentability in the EU if their technical teaching: “...requires the prior destruction of human embryos or their use as base material, whatever the stage at which that takes place and even if the description of the technical teaching claimed does not refer to the use of human embryos” has worrying implications for human embryonic stem cell (hESC) patents.

Decision of the German courts

The Brüstle decision resulted from a referral from the German Federal Court of Justice (BGH) during the appeal of a nullity action.

Following the CJEU’s ruling, the BGH found the hESC-related claims under consideration to be patentable when subject matter involving the destruction of embryos was removed from the claims using an ‘undisclosed disclaimer’ (a negative limitation absent from the specification).

Decision of the EPO opposition division

Since the BGH ruling would (at least at first) appear consistent with the European Patent Office’s (EPO’s) stated practice, it was surprising that the corresponding European patent (from which the German patent was derived) was subsequently revoked by the EPO during opposition proceedings.


The EPO’s stated position is that patent filings with an effective filing date of before June 10, 2008 (the online publication date of Chung et al, 2008, Cell Stem Cell, 2(2):113-117, which describes a method for obtaining hESC without destroying human embryos) must exclude subject matter requiring the destruction of human embryos from their claims.

However, in the Brüstle case, the opposition division (OD) found that disclaiming this subject matter from the claims led to addition of subject matter (impermissible under European law) for the following reasons:

A. Applying Enlarged Board of Appeal (EBA) decision G2/10, it resulted in a sub-group absent from the specification as filed; and

B. Applying EBA decision G1/03, ‘destructive methods’ could not be removed using an undisclosed disclaimer because:

(i) The remaining subject matter could not be obtained at the filing date without an inventive step or requiring additional information for a sufficient disclosure; and

(ii) An undisclosed disclaimer is unnecessary/ inappropriate since the patent over the claimed range offers sufficiently disclosed alternatives (ESC from non-human mammals).

Whereas decision G1/03 found that an undisclosed disclaimer could not add technical subject matter, decision G2/10 found that the subject matter remaining once a disclaimer had been applied could not add technical subject matter.

Subsequent decisions from the EPO’s Technical Boards of Appeal (TBA) found that only undisclosed disclaimers that pass both the G1/03 and G2/10 tests do not add subject matter, perhaps preventing the use of undisclosed disclaimers altogether.

The OD for the Brüstle patent appears to have applied this reasoning in reaching its decision.

Future implications

Examination of the interaction between G1/03 and G2/10 by other TBAs has resulted in more favourable conclusions for applicants. Decision T1870/08 noted the apparent contradiction between G1/03 and G2/10 but held that the G2/10 test does not apply to the technical features claimed, as such, but rather to the technical nature of the ‘invention’. An undisclosed disclaimer should not add subject matter if the claims both with and without the disclaimer solve the same technical problem(s) in the same way(s).

This interpretation potentially provides a means to apply the G1/03 and G2/10 tests and still allow the use of undisclosed disclaimers. Hence, if the OD’s revocation of the Brüstle patent is appealed, the patentee may be able to overcome reason (A), above.

Reasons (B)(i) and (B)(ii) may still prevent the use of undisclosed disclaimers in the Brüstle case. These reasons are fact-specific and do not necessarily have wider implications for hESC inventions. However, other problems may prevent a successful appeal of the OD’s decision.

First, G1/03 requires that an undisclosed disclaimer removes only the subject matter required to overcome a legal exclusion. The TBA may find that the undisclosed disclaimers used should exclude the destruction of human embryos only, rather than all embryos, as they currently appear to. However, this amendment may not be possible, since a granted patent is prohibited from broadening its scope of protection.

Second, if the patentee establishes that the specification as filed enables ‘non-destructive methods’ (as was established in the corresponding German case), then an undisclosed disclaimer would not be required or allowed since, at the date of filing, the relevant products could be obtained by ‘non-destructive’ methods, meaning no legal exclusion exists for these claims. The disclaimers would then have to be removed, again broadening the claim scope and putting the claims in an irreconcilable trap.

Finally, if the patentee does not establish that the specification as filed enables the generation of hESC without destroying human embryos, then an undisclosed disclaimer may be allowed. However, this would mean that the remaining subject matter would be unpatentable because it could not be performed by the skilled person at the effective date.

Accordingly, under current EPO practice, the Brüstle patent, and any other hESC filing with an effective date predating June 10, 2008 that requires the use of an undisclosed disclaimer, may be invalid.

Advice to applicants

If possible, the use of undisclosed disclaimers should be avoided for hESC inventions. As the EPO does not seem to require the exclusion of destructive methods for patent filings with an effective date of on or after it was possible to create hESC non-destructively, it could be argued, if necessary, that non-destructive methods were available before June 10, 2008. There appear to be reasonable arguments for such methods being available by 2006 and perhaps even 1997.

If claims including an undisclosed disclaimer have already been granted, and where nondestructive methods were available in any subsequent challenge, it could be argued that removal of the disclaimer does not extend the technical scope of protection.

Andy Sanderson is a senior associate at Potter Clarkson LLP. He can be contacted at andrew.sanderson@potterclarkson.com

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