In what may come as a welcome departure from existing practice, an EPO board of appeal in decision T1085/13 has clarified the conditions under which patents can be granted for known compounds at higher grades of purity.

A leading case concerning purity of materials has been T990/96 where it was held that a document disclosing a compound for the first time ordinarily makes the compound available in all desired grades of purity. EPO practice has been to view the earlier disclosure as novelty destroying to a later claim in which the same compound is claimed at a higher purity. To take an example, a document discloses a new dye, which is manufactured in 90% purity. The position based on T990/96 is to assume that that dye can be purified to all levels of purity by conventional methods and so is made available to the public in all desired grades of purity. Consequently, a later application claiming that dye in 95+% purity would lack novelty over the earlier disclosure.

The caveat has been that if the later applicant can demonstrate the existence of an “exceptional situation”, i.e. where all prior attempts to achieve a particular degree of purity by conventional purification processes have failed, then it might be possible to achieve grant of a patent for the known material at higher purity. The need to show an “exceptional situation” places a heavy burden on an applicant seeking a patent to a known material at higher purity. Furthermore, it is not a requirement that conventional purification methods must provide the higher purity in commercially relevant quantities. As was the case in T728/98, if the desired purity of compound could be prepared albeit in low amounts, e.g. by using an analytical technique such as HPLC, then that was sufficient to destroy the novelty of a later application claiming the material at higher purity.

In decision T1085/13 the board criticizes the existing line of case law as being inconsistent with decisions G2/88 and G2/10. The board emphasizes the need for a consistent approach to disclosure for the purposes of EPC Articles 54 (novelty), 87 (priority) and 123 (added subject matter) set out in G2/10. The Board clarifies that what matters for novelty is simply what the prior art discloses, taking implicit disclosure into account.

Essentially, what the board in T1085/13 have done is shift the issue of whether the known compound could be purified to the new level of purity from a question of novelty to a question of inventive step. This opens up the possibility of achieving novelty on the basis of purity and inventive step based upon an advantage associated with the new higher purity. It seems unlikely under this approach that the possibility of obtaining the compound at the desired purity using purely analytical techniques (as was the case in T728/98), would be enough to preclude later patent protection to the material at the higher purity where some valuable use of that material was also disclosed. It may still be the case that a higher grade of material is obvious over what has come before (particularly when no new techniques are required to achieve the required purity), but the consistency with the EPO’s approach to priority and added subject matter is welcome.