Intellectual property – guidance

Opinions: resolving patent disputes

If you are in a dispute with someone over the infringement or validity of a patent or SPC, you may request a non-binding opinion.


An opinion can help you negotiate a settlement or decide whether to proceed with full legal proceedings. An opinion is not binding on you or others involved. You can still proceed with full legal proceedings in the court or with us if you want to.

Our opinion is an independent assessment of the main issues in a dispute, prepared by one of our senior examiners. We base opinions on papers you and anyone else involved send us.

Requesting an opinion

Anyone can make a request for an opinion about infringement of a patent/supplementary protection certificate (SPC) or the validity of a patent/SPC. Your request must relate to a UK patent a European patent which designates the UK, or an SPC, whether it is in force or not.

To file a request, you need to complete and send us:

  • 2 copies of patents form 17 with the fee of £200
  • 2 copies of a statement setting out, in full, the facts of your case and your arguments or analysis with reference to which claims of the patent you would like the opinion to cover
  • 2 copies of any evidence or other documents you refer to in your statement, (you should provide translations for any documents not in English or Welsh)

You also need to tell us about:

  • any UK or EPO proceedings, which are either underway or have been completed and which relate to the patent/SPC
  • anyone who you know to have an interest in the opinion so that we can send them copies of your request

Any documents you send us will not be treated as confidential.

After you request an opinion

If we proceed with your opinion request, we will send a copy of all the documents we have received to other interested parties such as:

  • patent/SPC holder (including any exclusive licensee)
  • any holder of a licence or sub-licence
  • anyone who has filed a caveat relating to the request
  • anyone identified on patents form 17 as having an interest in the request and will invite them to make observations on your request. We will also advertise your request so that anyone else can make observations on it.

Refusal of a request

Under certain circumstances, for example when the issue in question has been decided before, we may think it right to refuse your request. If you disagree with us you will be given a chance to put your point of view in writing or at a hearing before a senior officer.

If we refuse your request, you may appeal our decision at the Patents Court.

Withdrawal of a request

If you want to withdraw your opinion request, all you need to do is write to us to let us know.

You can withdraw your request at any time, before or after we have advertised it.

We will notify relevant parties of the withdrawal and will update the register.

Making observations

Anyone can make observations on a request for an opinion.

You need to file observations within 4 weeks of the date of the advertisement of the request on our website. Observations must be confined to the issues raised in the request. An observer may file a reason about why he thinks we should refuse a request.

If it is reasonably possible you should send your observations by email. You should include the reference number of the opinion request. Our email address is You also need to send a copy to the person who filed the request, the patent/SPC owner and any exclusive licensee.

Your email may contain your observations or you can file these as an attachment to the email. We will try to read attachments in any format, but Microsoft® Word, WordPerfect, Portable Document Format (PDF) or plain text (RFC822 compliant) are preferred. If we are not able to read your attachment we will contact you.

Any material filed in relation to an opinion may also be open to public inspection, including on our website.

If no-one makes observations, we will base the opinion on the documents we have already received.

Making observations in reply

If you are:

  • the person who filed the request
  • the patent/SPC owner
  • an exclusive licensee

and someone has filed observations on your request, then you can file observations in reply.

Once the deadline for filing observations has expired, that is, 4 weeks after the request is advertised on our website, you will have 2 weeks to file observations in reply. You should send your observations in reply to us by email and should include the reference number of the opinion request. Our email address is

If you are the person who filed the request and are not the patent/SPC holder, you also need to send a copy of your observations in reply to the patent/SPC owner and any exclusive licensee.

If you are the patent/SPC holder (the owner of the patent/SPC or an exclusive licensee) and not the requester, you also need to send a copy of your observations to the requester.

We will write to you to let you know what action you need to take. We will not copy observations in reply to any other observers.

We will take your observations in reply into account when writing the opinion.

Extensions of time

The opinions process is quick - lasting no more than 3 months. Because of this time periods are short. Although you can ask us for an extension of time, you will need to have good reasons why you need this. Any extension is unlikely to be for more than a few days.

Issuing an opinion

When an opinion is ready, we will send a copy to:

  • you the requester
  • the patent/SPC owner(s) and any exclusive licensee (if not you)
  • anyone who filed observations

We will also advertise the outcome of your request.

If you disagree with the opinion, you may be able to challenge it.

Actions following issue of an opinion

We will not award damages if the opinion finds a particular act infringes the patent/SPC. If you decide to pursue an act of infringement as a result of the opinion, you can do so by filing infringement proceedings.

We may however start the process of revoking (cancelling) a patent if an opinion considers it to be invalid. This only applies in a limited set of circumstances. If we start this process, the patent holder will have the opportunity to:

  • apply for a review of the opinion (see below)
  • provide arguments or amend his patent to try to overcome the problem and prevent revocation
  • if the patent is revoked, appeal that decision to the courts

If we do not take such action, you may wish to file revocation proceedings yourself as a result of the opinion.


If you do not agree with an opinion, you might want to challenge it.

One way of challenging an opinion is to apply for it to be reviewed. A review consists of full legal proceedings here in the Intellectual Property Office. As a result of the proceedings, we will either agree with the opinion or we will set it aside.

There are many other ways of challenging an opinion. If you disagree with an opinion that says a patent is valid, for example, you could file revocation proceedings in the court or with us. These might result in the patent being cancelled. If you disagree with an opinion that says a particular act infringes a patent, you might want to file proceedings seeking a declaration of non-infringement.

Request a review

To apply for a review, you must be either the patent/SPC proprietor or an exclusive licensee, but even then, you can only apply for a review in certain circumstances.

You should file a patents patents form 2, statement of grounds, along with any copies of the documents referred to in your statement within 3 months of the date the opinion was issued. The 3 month period starts running on the day the opinion is issued, for example, if an opinion is issued on 15 January, a review must be filed by 14 April.

You can only apply for a review if you consider that:

  • the opinion wrongly concluded that the patent/SPC was invalid or partially valid
  • the opinion wrongly concluded that a particular act did not or would not infringe the patent/SPC

Within your application you cannot raise issues that have already been decided by the courts or us in other proceedings.

Next steps

If we proceed with your application for a review, we will send a copy of patents form 2, your statement and any other documents filed to:

  • the person who made the original request for an opinion, unless this is you
  • anyone who filed observations

and will invite them to file a statement supporting your application or a counter-statement opposing it. They will have:

  • four weeks from the date of advertisement or
  • two months from the date the opinion is issued, whichever is the later

in which to file a statement supporting your application or a counter-statement opposing it.

We will also advertise your application.

If no-one files a statement or counter-statement, the proceedings will just involve you.

If someone files a statement or counter-statement, we will send a copy of it to you. The proceedings will then involve you and the other party or parties.

Deciding review proceedings

We will usually appoint a hearing but if you and anyone else involved in the proceedings agrees, we will base our decision on the papers that have been filed. In either case we will issue a decision and will advertise it. We will also record the outcome of the review in the patents register.

You may be able to appeal the decision but the circumstances are limited.

You need to be either the patent/SPC owner or an exclusive licensee. Even then you can only appeal the decision if it upholds the opinion in whole or in part.

Anyone else involved in the proceedings does not have the right to appeal.

Award of costs

If the opinion is upheld on review, you should be aware that you may have to contribute to the legal costs of any other party involved in the review. These typically might run to £1000 or more.

Appealing a decision on a review

If you want to file an appeal you need to do so within the time limit set out in the review decision, which appears in the advertisement of the decision. Further details about appeals may be obtained from:

H M Courts & Tribunal Service
Royal Courts of Justice Group
Chancery Appeals Office
7 The Rolls Building
Fetter Lane

Telephone: +44 (0)20 7947 6890/6294/6243