Patent revocation under the Patents Act 1977 (as amended) is covered by Section 72.
Under this section, granted patents may be revoked at any time by the Comptroller or a court on the application of any person. This application to revoke must be on the following grounds.
a) The invention is not a patentable invention
b) That the patent was granted to a person who was not entitled to be granted that patent
c) The specification of the patent does not disclose the invention clearly enough for it to be performed by a person skilled in the art
d) The matter disclosed in the specification of the patent extends beyond that disclosed in the application for the patent, as filed, or, if the patent was granted on a new application filed under section 8(3), 12 or 37(4) above or as mentioned in section 15(9) above, in the earlier application, as filed
e) The protection conferred by the patent has been extended by an amendment which should not have been allowed.
Putting aside section 1(b) which has further clarifications in section 72, the ground for revocation need to be carefully considered in the drafting of a patent specification. All specifications should necessarily be drafted with an eye to infringement concerns, i.e. to be sure that a potential infringer will have the maximum difficulties in producing an article that avoids the patent claims, yet substantially copies the invention.
Subsection c) is particularly relevant to drafting. There must be enough detail in an application for it to be possible for a person skilled in the art to read the application and from it alone, with his general knowledge, make that invention. Many self-filed specifications do not contain enough detail for this.
In infringement proceedings and allegations, the immediate response of most infringers is to launch revocation proceedings.
So a draftsman must keep an eye on future revocation attempts. Even if the attorney gets it past the Examiner and proceeds to grant, many if not most, if not all, patents are liable to a successful revocation action later in their life at a court or even back at the Patent Office. For this reason a well-drafted specification will ideally be in a sense be doubly secure, once to overcome the Examiner and his objections, and once to overcome a court. Remember always that an Examiner generally wishes to grant patents, a court generally wishes to test them to their legal limits.