This guide is based on UK law. It was last updated in August 2018.
Under section 72 of the Patents Act 1977, a patent may be revoked for the following reasons:
- the invention is not a patentable invention. This subsection refers back to section 1(1) of the Act which requires that the invention is new, involves an inventive step and is capable of industrial application. A patent can be revoked if any of these requirements are not met.
- the patent was granted to a person who was not entitled to be granted that patent.
- the specification does not disclose the invention clearly and completely enough for it to be performed by a person skilled in the art.
- the matter disclosed in the specification extends beyond that disclosed in the application for the patent as filed.
- the protection conferred by the patent has been extended by an amendment which should not have been allowed.
Lack of novelty
A patent lacks novelty – is anticipated – if the alleged invention was already part of the 'state of the art' before the earliest claimed priority date. The state of the art comprises all matter, whether a product, a process, information about either or anything else, made available to the public before the priority date of the alleged invention. For novelty, the 'state of the art' also includes matter contained in patent applications which have an earlier priority date.
To anticipate a patent, the disclosure in the 'state of the art' must:
- disclose subject matter which, if performed, would necessarily infringe the claim; and
- disclose that subject-matter sufficiently to enable the skilled person to perform it.
A patent lacks inventive step – is obvious – if the alleged invention was obvious to the person skilled in the technical field of the invention as at the priority date of the patent, having regard to the 'state of the art' and the skilled person's common general knowledge. The state of the art for obviousness is as defined in section 2(2) of the Patents Act 1977 for novelty.
According to section 4(1) of the Patents Act 1977, as amended by the Patents Act 2004, "an invention shall be taken to be capable of industrial applicability if it can be made or used in any kind of industry, including agriculture". 'Industry' is to be construed widely to include any corporate enterprise.
Classical insufficiency occurs when the specification does not disclose the invention clearly and completely enough for it to be performed by the skilled person without undue effort. The relevant date for assessing insufficiency is the date of application.
'Biogen' insufficiency occurs when a claim extends beyond the technical contribution of the patent, thus not supporting the invention.
A patent can be found invalid for lack of plausibility, as a threshold test of sufficiency. This ground has developed more recently in order to distinguish patents that contain a teaching which is plausible to the skilled person from those that are entirely speculative.
A patent can be held invalid if it adds matter. This means that the scope of protection of the patent extends beyond that disclosed in the application for the patent as filed, as a result of amendments made during examination. Courts carry out the exercise of determining if there is added matter, through the eyes of the skilled person.
Intermediate generalisations are a particular form of added matter in which the patent specification provides a number of specific examples and the patentee seeks to generalise from these examples to claim a range or class the examples are said to illustrate.
Exclusions to patentability
Under section 1(2) of the Patents Act 1977, the following are excluded from patentability:
- discoveries, scientific theories and mathematical methods;
- aesthetic creations (including literary, dramatic, musical and artistic work);
- a scheme, rule or method for performing a mental act, playing a game or doing business, or a program for a computer; and
- the presentation of information
These are construed narrowly, so a patent or application will not be treated as an invention if it falls within any of the above.
The primary remedy sought in a revocation action is a declaration by the court that the patent is invalid and an order for the unconditional revocation of the patent.
A patent can be found to be partially invalid i.e. some claims are invalid, some valid. The court may revoke the patent unless, within a specified time, the specification is amended to the satisfaction of the court, under section 72(4) and section 75 of the Patents Act 1977.
Amendments in revocation/cancellation proceedings
Where a patent is subject to revocation proceedings, the patent owner can apply to the court, or the comptroller general of patents, designs and trade marks at the UK's Intellectual Property Office (IPO), for an amendment to the claims of the patent. A person may give notice of their opposition to an amendment proposed under section 75 of the Patents Act 1977. The court, or comptroller, will notify the proprietor and consider the opposition in deciding whether the amendment should be allowed.
An amendment of a specification of a patent under section 75 shall have the effect and be deemed always to have had effect from the grant of the patent, according to section 75(3) of the 1977 Act.
This amendment procedure is governed by Civil Procedure Rules (CPR) Part 63.10.
The application to amend should be made in writing, must identify the proposed amendment, must state the grounds on which it is based and it must state whether the patent owner contends that the claims in their un-amended form are valid. The amendment can be sought on a conditional or unconditional basis. The application notice must be served on the comptroller as well as other parties to the litigation within seven days. Unless the court orders otherwise, the application must be advertised in the IPO's official patents journal.
Revocation/cancellation and infringement
In courts in the UK, revocation and infringement proceedings are heard together.