Manual of Patent Practice

Section 75: Amendment of patent in infringement or revocation proceedings

Sections (75.01 - 75.21.1) last updated: July 2018.


This section is concerned with the amendment of the specification of a granted patent, including a European patent (UK), during proceedings in which the validity of the patent may be put in issue. Such proceedings are defined in s.74(1), and the definition is somewhat broader than the title of s.75 might appear to imply. It does not include revocation proceedings initiated by the comptroller under s.73. The Patents Act 2004 amended s.75(1) to remove the necessity for validity to have been put in issue before a proprietor can apply to amend under s.75. For proceedings brought on or after 1 January 2005, a patent proprietor can propose amendments during the course of any proceedings in which it is possible for the validity of the patent to be put in issue, whether or not validity has actually been raised.


In Chiron Corp v Organon Teknika Ltd [1994] FSR 258 Aldous J held that s.74 does not bar an opponent from raising lack of support under s.14(5)(c) in amendment proceedings. He was also upheld on appeal ([1995] FSR 559) in finding that a proposal to delete claims, which had been found to be invalid, should not open the door to an allegation that other valid claims lacked support, when the proposed amendment did not impinge on the invention claimed in the valid claims. In particular, Aldous J concluded that there was no justification for requiring amendment of the valid claims to disclaim the matter of the claims to be deleted.


There are two distinct procedures, depending on whether the proceedings are taking place before the comptroller or the court. In the former case the procedure is governed by Part 7 of the Patents Rules 2007, while in the latter case it is subject to rule 63.10 of Part 63 of the Civil Procedure Rules 1998 (CPR 63) and section 12 of the Practice Direction supplementing CPR 63 (CPR 63PD). Further information concerning procedures before the court is provided in The Patents Court Guide available through the website of the Court Service. It should also be noted that slightly different procedures again apply where the proceedings are before the Court of Session. These are not detailed below, but are governed by paragraph 55.5 of the Rules of the Court of Session.


s.74(8), CPR and 63.10(3) are also relevant.

Rule 35(2) requires a proposed amendment to a specification of a patent to be delivered in electronic form or using electronic communications if reasonably possible. Similarly, CPR 63 requires the application notice for permission to amend under s.75 before the court to be served on the comptroller electronically if reasonably possible. Directions prescribing the form and manner for electronic delivery of applications to amend under s.75 were published in the PDJ No. 5938 on 12 March 2003, and came into force with the Patents Act 1977 (Electronic Communications Order) 2003 (S.I. 2003 No. 512) on 1 April 2003. Electronic delivery should be made either by email to entitled “Proposal to amend under s.75 before the comptroller [or the courts]” as appropriate, or on an electronic carrier delivered to the Office accompanied by an identifying letter see 27.03.1 and the Directions for further information on the formats for electronic submission).



Section 75(1)

Section 75(1)
In any proceedings before the court or the comptroller in which the validity of a patent may be put in issue the court or, as the case may be, the comptroller may, subject to section 76 below, allow the proprietor of the patent to amend the specification of the patent in such manner, and subject to such terms as to advertising the proposed amendment and as to costs, expenses or otherwise, as the court or comptroller thinks fit.

Exercising discretion


The allowance of amendments is a matter of discretion and similar considerations apply as under s.27 see 27.07-27.11.1, 27.11 and 27.32. However, section 75(5) was added on 13 December 2007 and provides that in considering whether to allow a proposed amendment the court or comptroller shall have regard to relevant principles under the European Patent Convention (EPC) (see 75.21 and 75.21.1). Various judgments provide discussion of the exercise of discretion prior to the introduction of s.75(5). The extent to which these cases are now relevant is set out below.

In Smith Kline & French Laboratories Ltd v Evans Medical Ltd [1989] FSR 561, Aldous J identified the following principles concerning discretion as to whether or not to allow amendment

(i) the onus to establish that amendment should be allowed is upon the patentee and full disclosure must be made of all relevant matters;

(ii) amendment will be allowed provided the amendments are permitted under the Act and no circumstances arise which would lead the court to refuse the amendment;

(iii) it is in the public interest that amendment is sought promptly, so a patentee who delays for an unreasonable period before seeking amendment must show reasonable grounds for his delay; This principle is no longer relevant in light of s.75(5).

(iv) a patentee who seeks to obtain an unfair advantage from a patent, which he knows or should have known should be amended, will not be allowed to amend;

(v) the court is concerned with the conduct of the patentee and not with the merit of the invention. This principle is no longer relevant in light of s.75(5).

The exercise of discretion was also discussed by the Court of Appeal in Kimberly-Clark Worldwide Inc v Procter & Gamble Ltd ([2000] RPC 422). However, the intended effect of s.75(5) is that the old law relating to covetousness and delay is swept away and these matters are no longer an issue in post-grant amendment (see 75.21 and 75.21.1). This effect was explicitly confirmed by Floyd J in Zipher Ltd v Markem Systems Ltd & Anr [2008] EWCH 1379 (Pat):

‘It follows that if I am to have regard to the principles applicable under the EPC, the discretion which I have to refuse amendments which comply with the Act has been limited. Considerations such as those formerly considered relevant to the discretion, such as the conduct of the patentee, are no longer relevant.’ r.35(6)


r.38(6) is also relevant.

It is considered that the above factors apply not only to the allowance of amendments but also to whether to give an opportunity to amend. In ICI Plc v Ram Bathrooms Plc and Rohm GmbH ([1994] FSR 181) Aldous J held that, in actions where the parties have in effect settled their dispute, he would only allow patents to be amended where (a) the amendments are not substantial in amount or effect; (b) there is no apparent matter of controversy; and (c) no matter of public interest arises. It follows that if any of these matters exist the patentee should apply to the comptroller for amendment under s.27. Jacob J allowed amendment in Mabuchi Motor KK’s Patents [1996] RPC 387 despite a patent in question not having been framed with reasonable skill and knowledge and despite the proprietors being dilatory in pursuing the matter of amendment after having started proceedings, because no actual or likely prejudice to the public had been shown and interested parties could have learnt of the existence of the amendment proceedings from the register. It may also be made a condition for allowing the amendments that a new specification or replacement pages be provided, in the same way as described in 27.18. However, when comparing ss.27 and 75, the hearing officer in Osterman’s Patent [1985]

RPC 579 held that where the application to amend is under s.75 there is a difference; the Act and the Rules make no specific provision for the giving of reasons, because there is a presumption (in proceedings under s.72) that the amendments are offered with a view to meeting the grounds for revocation. (Note that the proprietor may amend his patent centrally before the EPO to meet the grounds for revocation see 72.44.1. He declined to direct that the patentees should give evidence directed towards the proposed amendments, and in particular the reasons for them, prior to the applicants for revocation giving their evidence in chief on those amendments and on the revocation issue. The Patents Court held that the hearing officer had not wrongly exercised his discretion.


In Koninklijke Philips Electronics n.v. v Nintendo of Europe GmbH [2014] EWHC 1959 (Pat) the Patents Court found that a double patenting objection taken as a ground for refusing a post-grant amendment to a claim can be taken but should only be made in the following circumstances:

i) The two patents must have the same priority dates and be held by the same applicant (or its successor in title);

ii) The two claims must be for the same invention, that is to say they must be for the same subject matter and have the same scope. The scope is considered as a matter of substance. Trivial differences in wording will not avoid the objection but if one claim covers embodiments which the other claim does not, then the objection does not arise.

iii) The two claims must be independent claims. If two independent claims have different scope then there is no reason to object even if the patents contain dependent claims with the same scope.

If the objection arises, and both patents are before the comptroller or court, then it can be cured by an amendment or amendments to either patent. Even if the objection properly arises in the sense that two relevant claims have the same scope, if the patentee has a legitimate interest in maintaining both claims then the amendment should not be refused (see paragraphs 296-309 of the judgment).

Amendment during proceedings before the comptroller


Much of what follows in paragraph 75.07 relates specifically to amendment during revocation proceedings under s.72, but is applicable mutatis mutandis to other proceedings in which validity is put in issue. The outcome of any offer to amend the patent is recorded in the Register.


r.75 is also relevant.

When amendments have been proposed during a hearing see 72.42 or following an interim decision see 72.44 the Comptroller has discretion as to whether or not to advertise them in the Journal as open to opposition. In exercising this discretion, the comptroller will consider how significant the amendments are and the likelihood of another party wishing to object. Where the amendments are being proposed to avoid revocation it is likely they will be significant amendments to which another party may wish to object. If however the amendments are clearly not allowable, or would not cure invalidity, or are clearly minor, then the comptroller may consider that advertisement is not necessary. Where an amendment is advertised in the Journal,copies of the amendment are available through Tribunal Section, and, if the amendment has been filed electronically, through the website. The amendments will be available in the form subsisting after the proprietor has considered any objection to them by the Office or by the other party. The hearing officer will normally defer issuing a final decision terminating the proceedings until the period allowed for opposing the amendments see 75.15 has expired or until any opposition has been resolved.

[ If it is decided that the amendments should be advertised as open to opposition, Tribunal Section is responsible for seeing that this is done. ]



Amendment during proceeding before the court


CPR 6.10(1) is also relevant.

An application to the court under section 75 of the 1977 Act for permission 63.10(1) to amend the specification of a patent by the proprietor of the patent must be made by application notice.


CPR63.10(2) is also relevant.

The application notice must

(a) give particulars of -

(i) the proposed amendment sought; and

(ii) the grounds upon which the amendment is sought;

(b) state whether the applicant will contend that the claims prior to amendment are valid;

(c) be served by the applicant on all parties and the comptroller within 7 days of its issue.

General rules about applications for court orders are governed by Part 23 of the Civil Procedure Rules.


CPR 63.10(3), CPD 63PD para 12.2 is also relevant.

The application notice must, if it is reasonably possible, be served on the comptroller electronically. When served electronically, the application notice must comply with any requirements for the sending of electronic communications to the comptroller see Directions under section 124A, Submitting post-grant amendments by e-mail, and also 27.03.1 and 75.02.1.


CPR 63.10(4) is also relevant

Unless the Court otherwise orders, the comptroller will forthwith advertise the application to amend in the Journal.


CPR 63.10(5) is also relevant.

The advertisement will contain an electronic copy of the amendments or will state that any person may apply to the comptroller for a copy of the application notice.


CPR 63.10(6) is also relevant.

Within 14 days of the first appearance of the advertisement any person who wishes to oppose the application must file and serve on all parties and the comptroller a notice opposing the application which must include the grounds relied on.

[ Any notice opposing the application should be forwarded to the Deputy Director responsible for preparing the comptroller’s comments on the proposed amendments (see 75.12).]


CPR 63.10(7) is also relevant.

Within 28 days of the first appearance of the advertisement the applicant must apply to the Court for directions.


A report should be prepared in the Office for the benefit of the Court on the question as to whether the proposals are considered by the Office to be prima facie allowable. In general, the Office need only consider whether the amendments meet the requirements of ss.14(5) and 76: there is no point in considering whether they meet any objection that has been raised as to, e.g. lack of novelty, obviousness or insufficiency, because these are likely to be considered by the court with the benefit of material to which the comptroller does not have access. In order to avoid any misunderstanding that the Office has considered all aspects relevant to allowance of the amendment, the report should make clear that the Office’s consideration has only extended to ss.14(5) and 76. In addition, if the amendments appear prima facie allowable the report should say that the comptroller considers that the amendments meet the requirements of these sections, but if they are not prima facie allowable the reason for this should be explained in the report. All parties to the proceedings before the court should be informed of the Office views on the amendments and whether the comptroller has decided to be represented in Court. The Office does not normally communicate the report direct to the Court but instead asks the applicant to pass it on see 75.20. In paragraph 128 of L’Oréal Ltd v RN Ventures Ltd [2018] EWHC 173 (Pat), Carr J discusses the report prepared in this case and agrees with it. Further judgments which discuss the report prepared by the Office include Curt G Joan Inc v Fameccanica Data SpA [2017] EWHC 1251 (IPEC) and Cantel Medical et al v Arc Medical [2018] EWHC 345 (Pat).

[ The application to amend should be referred for the report as soon as advertisement has been arranged, but the report generally should not be finalised or issued until the 14 day opposition period has passed (see 75.11), which will allow any notice opposing the application to be taken into account. The Deputy Director in charge of the subject-matter concerned is responsible for preparing the report or having it prepared. The report may take the form of a letter to the applicant informing him of the comptroller’s views. It is for the Court to decide ultimately on the allowability of the amendments and the Office merely gives its views without becoming involved in the discussion.]


CPR 63.10(3), CPR 63PD para 12.2 are also relevant.

Not less than 2 days before the first hearing date, the applicant, the comptroller if he wishes to be heard, the parties to the proceedings and any other opponent, must file and serve a document stating the directions sought.


CPR 63.10(8) is also relevant.

Unless the Court otherwise orders, the applicant must within 7 days serve on the comptroller any order of the Court on the application.

[ Where the specification should be amended by Tribunal Section who will also prepare the appropriate certificate Court allows a specification to be amended, the original copy of the (s) for the signature of the Deputy Director. The Deputy Director is thus responsible for approving the wording of the certificate and certifying that the amendments comply with the Court order. It should be noted that the Deputy Director concerned is not acting for the comptroller in this particular situation since the allowability of the amendments has been decided by the Court. ]

[ A decision by the Court or comptroller to allow an amendment should be actioned immediately and not deferred if an appeal is entered, unless the decision has been stayed pending appeal. Accordingly appropriate Register/Journal entries should be made and the Office copy, ie the authentic version of the patent specification, should be amended. Notice of any appeal should be entered into the Register/Journal to advise the public of the potential transient nature of the decision. It is also desirable that the public should have a published version of the amended patent as soon as reasonably possible. Thus, unless the Office is aware that an early date for an appeal hearing has been fixed, a ‘C’ publication should be produced with a footnote that the decision to allow the amendment is under appeal as of a certain date. A ‘C’ publication of the amended patent without the footnote should not be produced once the final appeal has been disposed of unless the final appeal further amends the patent. The procedure for production of the ‘C’ publication is as described in 27.20. If a decision by the Court or comptroller has been stayed pending an appeal and an appeal has been lodged, the Office will note the Register and Journal that the decision is stayed pending appeal and that an appeal has been lodged on a certain date. ]

Section 75(2)

Section 75(2)
A person may give notice to the court or the comptroller of his opposition to an amendment proposed by the proprietor of the patent under this section, and if he does so the court or the comptroller shall notify the proprietor and consider the opposition in deciding whether the amendment or any amendment should be allowed.


The considerations referred to in 27.24 and 27.28 also apply to an opposition under s.75.

Opposition to amendment before the comptoller


PR part 7, r.75, r.76(2)(a) and r.108(1) are also relevant.

Where in any proceedings before him, the comptroller requires an amendment proposed under s.75 to be advertised, notice of the amendment is advertised in the Journal, stating that details of the amendment are available through Tribunal Section, and if the amendment has been filed electronically, through the website. Notice of opposition should be given on Form 15 which should be filed within two weeks of the date of the advertisement of the amendments sought; this period may not be extended. The form should be accompanied by a copy thereof and a statement of grounds (in duplicate). This starts opposition proceedings before the comptroller, the procedure for which is discussed at 123.05 – 123.05.13. However, if an applicant for revocation has opposed an amendment offered by the proprietor during revocation proceedings, the applicant for revocation does not subsequently need also to give notice of opposition to the amendment on Form 15 Eickhoff Maschinenfabrik’s Patent, BL O/031/87; Harding’s Patent, BL O/094/90.


In Ability International Ltd v Monkey Tower Ltd (BL O/484/14), the hearing officer decided that any opposition to amendment under s.75 must be limited to questioning whether the amendment overcomes the stated defects (that is, the defects which led to the amendment request), and whether the amendment meets the requirements of s.76. A similar limitation applies in opposition proceedings to amendments made under s.27 see 27.28.


r.77(1) and (r.77(2) are also relevant.

The Office will send a copy of the notice of opposition and the statement to r.77(2) the proprietor and to any other party to the proceedings before the comptroller.


The comptroller may stay the other proceedings and decide the opposition,if necessary at a hearing, or may decide both actions together.

Opposition to amendment before the court


See 75.11.

Section 75(3)

Section 75(3)
An amendment of a specification of a patent under this section shall have effect and be deemed always to have had effect from the grant of the patent.


See 27.22.

Section 75(4)

Section 75(4))
Where an application for an order under this section is made to the court, the applicant shall notify the comptroller, who shall be entitled to appear and be heard and shall appear if so directed by the court.


See also 75.12. If, as is normally the case, the comptroller is not to be represented, the applicant should be asked to inform the Court of the comptroller’s views. The Court may, however, decide that the comptroller should be represented.

Section 75(5) In considering whether or not to allow an amendment proposed under this section, the court or the comptroller shall have regard to any relevant principles applicable under the European Patent Convention.


Section 75(5) confers on the comptroller or court discretion to allow or refuse an amendment to the patent. Articles 105a(1) and 123 EPC also confer on the EPO discretion to allow or refuse an amendment of the European patent. The comptroller or court continue to have discretion to allow or refuse an amendment, but in exercising that discretion, section 75(5) requires the comptroller or court to have regard to any relevant principles which are applicable to amendment or limitation proceedings under the EPC. These may include relevant regulations made under the EPC, any relevant guidelines produced by the EPO, and decisions of the Opposition Division and Boards of Appeal. This should ensure that, as far as possible, there is consistency in approach as regards postgrant amendment in national proceedings and before the EPO. The EPO do not consider the behaviour of the patent proprietor when exercising discretion in allowing amendments. The intended effect of section 75(5) is that the behaviour of the patent proprietor will no longer be an issue to be considered in the UK when deciding whether to allow an amendment to be made under section 75. This effect was confirmed by Floyd J in Zipher v Markem see 75.04 and below.


In Zipher Ltd v Markem Systems Ltd & Anr [2008] EWCH 1379 (Pat), Justice Floyd summarised the position under the EPC as follows: i) in opposition proceedings, appropriateness of the amendments to the proceedings, their necessity and procedural fairness are the main, perhaps only, factors considered relevant to the discretion to allow amendment; ii) in central amendment proceedings, compliance with the procedural requirements gives rise to a right to have the patent limited in accordance with the request.

These are therefore the factors which should be taken into account when considering whether or not to allow an amendment under this section.