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The Expensive Exchange of Ideas

If you intend to buy or license someone else's patent, then you should let the Intellectual Property Office (IPO) know.

Buying someone else’s patent

If you buy someone else’s patent it is important to inform the Intellectual Property Office (IPO) so that they can record the change of ownership. The legal term for this process is assignment. You must complete a Form 21 and send it with a £50 fee.

Licensing someone else’s patent

You can use a patent as long as the owner has given you a licence to do so. Many patents are listed in the Licence of Right, which means anyone has the right to license under that patent. The IPO will not get involved in licence disputes, excluding Licence of Right. It is advisable to tell the IPO of the licence so they can then record it on the register of patents. You must also fill in a form 21 and send it with the £50 fee.

Freedom to operate patent search

If you are worried that your idea or invention may incorporate an element which has already been patented, you can pay to get a freedom to operate search, which will highlight any technology which you may infringe upon if you try to patent your item. If there are already elements which are patented you can approach the patent holder for a licence or look elsewhere. A freedom to operate search is quite a costly process but it can, in turn, prevent even more costly mistakes.

Patent infringement

It is against the law to use someone else's patent without getting permission from them first. If you do use someone else's patent behind their back, you can be sued.

If someone sues you for infringing their patent, there are two main lines of defence; firstly that you are not actually infringing their patent and secondly that their patent is not valid. If you win in the second instance, their patent will be revoked.

It is always a good idea to try and avoid infringing another patent you can do this by asking for an opinion or paying for a freedom to operate search.


If you believe that an invention for which someone is applying for patent is not new, you can make an observation, which will be referred to when the IPO are making its decision. Observations can only be made after the application has been published and before the patent has been granted. You can view published applications on the IPO website and should ensure that your observation has not already been made before you raise it.