Firstly, registering the licence ensures that any person who subsequently acquires rights in the patent is effectively put on notice of the licence holder's rights. This may include assignees of the patent or other subsequent license holders.

Secondly, registration of an exclusive license confers several benefits including:

(a) the exclusive licensee is able to easily show that they are entitled to bring an infringement claim (where, for example, the patent owner does not wish to pursue litigation themselves); and if the patent litigation proceedings are successful, an exclusive licensee will be entitled to recover their legal costs and expenses from the infringer; and

(b) if an exclusive patent license is not registered with the UK Intellectual Property Office within six months of the date of the licence agreement, then in accordance with the rules contained in the Patents Act 1977 an exclusive licensee will forfeit their right to claim legal costs and expenses against the infringing party.

A recent case (highlighted by my colleague Paul Cox in the article below) demonstrates how the Courts are applying these rules stringently.