Essential Features of Compound Inventions

Date Published

When a claim is directed to a compound having a specific structural formula, the structure is an essential feature. Whilst it is possible that there are inessential parts of the structure, this would not normally be the case. During examination, it should be presumed that all features of a structure are essential, unless there are sound arguments to the contrary.

See American Home Products Corporation Application [1994] APO 58.

In order to establish that a particular group in a structure is not essential to the activity of a compound, it will usually be necessary to demonstrate that the activity is present when that group is absent (i.e. replaced by hydrogen) and when the group is replaced by different groups, for example groups that are neither isosteric nor isoelectronic.

See Rohm and Haas Co v Nippon Kayaku Kabushiki Kaisha and Sankyo Co, Ltd [1997] APO 40 and Beecham Group Ltd v Bristol Laboratories Ltd [1978] RPC 153.