There was little case law on this issue in the early days of the European Patent Convention. However, there have been a number of cases in the past few years that show development of the law in this area. In Genentech/Polypeptide expression I[1] the Appeal Board indicated that the essential requirement is that at least one way of carrying out the invention is disclosed such that one skilled in the art can carry it out. This caused some confusion for a while in cases where multiple embodiments were covered by the claims. It now seems clear that what was meant was that one need only describe one way to put the invention into practice as long as that method is of general application throughout the full scope of the claim. The Genentech decision did, however, point out that there is a "general legal principle that the extent of the patent monopoly, as defined by the claims, should correspond to the technical contribution to the art in order for it to be supported or justified. The case is of significance in the area of biotechnology in noting that non-availability of some particular variants of a functionally defined component is immaterial to sufficiency as long as there are suitable variants known to the skilled person through the disclosure or common general knowledge.

In Fuel oils/Exxon[2] a distinction was drawn between cases where one method was described that was of general applicability throughout the range of what was claimed and other situations where, for example, chemical compounds claimed in an application could not all be produced by the described method or by the application of common general knowledge.[3]

In the Exxon case itself, a claim to a fuel oil containing small wax crystals was held to lack support in the description because this had taught that certain additives were necessary to achieve the stated size range and the claim made no reference to such additives. Claims need to be commensurate with the technical consideration described in the specification if they are to be regarded as properly supported.[4] Thus if, as in the Exxon case, the specification states that certain features are essential to produced the promised result, a claim that lacks those features is not supported by the specification. [5]

The mere fact that some functionally defined starting materials may not be suitable does not in itself render the specification insufficient.[6] Furthermore, it has been held that lack of an Example in a chemical case similarly in itself does not render the specification insufficient.[7] In Redox Catalyst/Air Products[8] the Appeal Board excused an error in the specification on the ground that it was immaterial to the sufficiency of the disclosure if the skilled man could recognize what was required using his common general knowledge. It was, however, pointed out that "no undue effort was [to be] expected from the skilled man either in the way of ... [a] search or experimentation, let alone any necessity to exercise his inventive skill."

In Human t-PA/Genentech[9] an EPO Technical Board of Appeal dealt with two key issues relating to protection of inventions relating to genetic engineering. The first was the question of what disclosure is required to support a claim to a specific amino acid sequence. The second is how precisely must the functions of a material which is defined in functional terms themselves be defined.

The first issue cams up in connection with the question of whether a claim that specified a particular amino acid sequence for a polypeptide was entitled to the priority date of an application that described what was said to be the same material but which had as a result of sequencing errors identified some of the amino acids in the sequence differently (three of the amino acids in a polypeptide containing 527 amino acids). The Board held that the structure of the polypeptide was one of its essential characteristics, particularly in view of the fact that changing only one or two amino acids could change its properties, so that even though the priority documents had described a method of producing the polypeptide, a claim directed to that polypeptide as such and characterized by the amino acid sequence in question was not entitled to that priority date, holding that

Priority was therefore refused. The Board in reaching its conclusion observed that in the field of protein chemistry minor changes in amino acid sequences can effect major changes in the folding and other properties of the protein and hence of its biological properties. Tough as the decision is, it is consistent with that in Chroman derivatives/Merck where an attempt to replace an incorrect chemical formula was refused even when it was clear that the teaching of the Examples inevitably resulted in compounds of that formula because the effect of the amendment would have been to add crucial information not contained in the original document.[10]

The second issue came up in the context of a claim reading as follows:

In dealing with this claim, the Board first had to consider whether an objection could be taken in opposition proceedings that the claims lacked clarity and were unsupported by the disclosure. The grounds under which oppositions can be made are set out in Article 100 of the European Patent Convention and do not specifically include lack of clarity and undue breadth, although under Article 84, both of these grounds can be relied upon by the Examining division during initial examination of the application. In the present case, the board concluded that since the wording in question arose form an amendment offered by the patentee, it did have jurisdiction to consider whether the amended claims met the requirements of Article 84. (The unexpressed reason apparently being that one should not be allowed to secure by amendment after grant what one could not have secured before grant in normal prosecution). Once this was done, the Board had no trouble in finding that a specification describing how to produce human t-PA and certain functions to test for in certain claimed derivatives thereof was not sufficient to support broad claims to either a process for preparing or a DNA isolate "obtainable " by a particular process where the DNA was defined by a partial structure and the fact that it coded for "a protein which has tissue plasminogen activator function" on the ground that this latter term was unduly broad and vague. The Board commented "Human t-PA is a molecule with multiple functions, some of which are in common with other molecules ... Therefore a reference which fails to characterize the precise functions meant is of no assistance to the skilled addressee. The claim was therefore both insufficient and lacking in clarity. However, it was held the specification did contain sufficient disclosure to support claims to such a process when specific functions associated with human t-PA were included, despite the absence of the lack of a single example of a functional derivative in the description. The board found that

The moral of this case may be therefore that when dealing with inventions in this area of technology one should be careful to ensure that sequences set out in a specification are correct, give as clear a set of general instructions as possible as to how produce the desired product in case one is forced to rely on product-by process protection and make absolutely clear what functions one is referring to when attempting to define a product by its function.

As noted later in the discussion under national law of the English decision in Biogen v. Madeva a conflict rose between the EPO and the English courts over whether the claims of the patent in suit were entitled to their claimed earliest priority date. At this point all we need note is that the EPO noted that there were certain elements that were missing from the initial disclosure but concluded that these were implied by the text and could be implemented by a simple experimental approach.