IP Cases & Articles

Assignments overview and pitfalls to beware!

Many patents will see a change in ownership at some stage in their lives. Assignments are commonplace and occur for a variety of reasons; for example, in the context of a business sale where a buyer purchases all of the assets (including intellectual property assets) of a business from the vendor. Another is in the context of intra-group reorganisations.

Assignments can also occur as part of settlement of a dispute. This article outlines some of the pitfalls of which you should be aware when assigning patents; many of which can be averted by careful drafting of the assignment agreement.

Unless the assignment is intra-group, there will usually be some distance between what the assignee wants (typically, a variety of representations, warranties and indemnities in respect of the assigned rights) and what the assignor is prepared to give. This is a commercial decision and hence no two negotiated patent assignments will be identical.



Under English law, to be a valid contract there must be consideration which is either money or money's worth. This is often overlooked but a key point required for the assignment agreement to be legally binding. Whilst the acceptance of mutual obligations may suffice, it is simplest to have a sum of money (even if only for £1). An alternative is to execute the assignment as a deed, though there are specific formalities which must be followed for the agreement to be a deed. Of course, if the parties agree to nominal consideration (eg, £1), it is important that this small amount is actually paid to the assignor.


An assignment of a UK patent (or application) must be in writing and signed by the assignor. It used to be the case that an assignment of a UK patent (or application) would need to be signed by both parties, however the law was changed in 2005. In reality, both parties will usually sign the assignment agreement. Where one or both of the parties is an individual in their personal capacity or a foreign entity, special 'testimonial' provisions are required; for example the signature to the assignment may need to be witnessed.

The assignment

English law distinguishes two types of assignment: legal and equitable. To assign the legal interest in something means that you have assigned simply the title to that property and not the right to exercise the rights inherent in it. This is the equitable (beneficial) interest and if this is not also assigned with the legal title, this can result in a split in ownership. Unless the parties specifically agree otherwise, legal and beneficial ownership should always be assigned together. It is possible to have co-assignees (ie, co-owners) but the terms of the co-ownership will need to be carefully considered.

It is possible to assign the right to bring proceedings for past infringements in the UK, but not in some other jurisdictions. Where non-UK rights are involved, local advice may be required as to whether such an assignment would be enforceable as against a prior infringer. This potential uncertainty makes a robust further assurance clause even more desirable (see below), to ensure the assignor's co-operation after completion of the assignment.

The assignee will also typically argue for (and the assignor will typically resist) a transfer with 'full title guarantee', as this implies as a matter of law certain covenants: that the assignor is entitled to sell the property; that the assignor will do all it reasonably can, at its own expense, to vest title to the property in the assignee; and that the property is free from various third party rights.

In terms of European patents (EP), it is important to remember that ownership of an EP application is determined under by the inventor/applicant's local law, rather than under European patent law. This means that a formal, written assignment agreement should be executed to ensure that the applicant is entitled to ownership of the patent application, for example in cases where the work undertaken was done by a consultant or where local law dictates that the owner is the inventor(s). An assignment should include assignment of the right to claim priority, as well as the right to the invention and any patent applications. This need to obtain an effective assignment of the application (and right to claim priority) is particularly important where a priority application has been made in the name of the inventor. If such an assignment is not executed before applications which claim priority from earlier cases (for example, PCT applications) are filed, the right to ownership and/or the right to claim priority may be lost.

Don't forget tax

Currently, there is no stamp duty payable on the assignment of intellectual property in the UK. However, particularly for assignments which include foreign intellectual property rights, there can be considerable tax implications in transferring ownership of intellectual property rights in some countries and it is always prudent to check that the transfer will not result in excessive tax liabilities for you.

Update the register

Registered rights need to be updated at the patent offices. You will need to decide who pays for this: in the case of one patent, it is a simple process, however in the case of a whole portfolio, the costs can be considerable. Remember, if you ever need to take any action on a patent you own, you need to ensure you are the registered owner of that right at the applicable office.

In the UK, assignments can be registered but there is no statutory requirement to do so. In the case of international assignments, local offices may require recordal of the assignment. In any event, it is desirable for an assignee to ensure that the transaction is recorded. Section 68 of the UK Patents Act provides that an assignee who does not register the assignment within six months runs the risk of not being able to claim costs or expenses in infringement proceedings for an infringement that occurred before registration of the assignment, although recent case-law has reduced this risk somewhat.

Further assurance

The assignee will typically take charge of recordals to the Patents Offices; however they will often need the assignor's help in doing so. A 'further assurance' clause is a key element of the assignment from an assignee's point of view both for this purpose and for assisting in the defence and enforcement of patents or applications for registration. On the other hand, the assignor will typically seek to qualify its further assurance covenant by limiting it to what the assignee may reasonably require, and that anything done should be at the assignee's expense. An assignor should also require that recordals are done promptly to minimise their future correspondence from patent offices.

International transactions

In transactions which involve the transfer of patents in various countries, the parties can execute a global assignment which covers all the patents being transferred, or there can be separate assignments for each country. The former, global assignment, is usually preferred however this will frequently need to be supplemented by further confirmatory assignments in forms prescribed by the relevant international patent registries. As noted above, the preparation and execution of such assignments can be time-consuming and costly, hence the need to decide in advance who bears the cost of such recordals, and the assignee should insist on a further assurance provision.