The union trademark remains one of the main achievements of the EU Trade Mark system. The success is mainly based on the fact that the Union trade mark allows to obtain an exclusive right in all member states at a reasonable costs by filing one application resp. registration at the Union trademark at the European Union Intellectual Property Office (EUIPO).
The (trademark) consequences of a possible withdrawal of a Member State from the Union aren`t regulated by law. Neither does the Regulation (EC) No 2015/2424 (Union Trade Mark regulation) provide any clause concerning property rights in the event that a Member State may withdraw from the Union nor is the Union Trade Mark regulation applicable to the states outside the EU.
Furthermore, in the event of a withdrawal of a Member State, the EU has no exclusive regulatory competence.
Once a Member State decides to withdraw, the Lisbon Treaty requires to notify the European Council of the intention to withdraw. Upon notice, there will be a two years` term, jointly extendable, to negotiate a Withdrawal Agreement, containing a framework for the future relationship between the withdrawing state and the EU. Until the end of this term or an unanimous term resp. an absent agreement, all Union Treaties, rights and obligations would cease to apply in withdrawing state (Art. 50  TEU).
On 23 June 2016 the UK voted to leave the EU, and thereby decided for what has become known as Brexit. As of today, it is still uncertain what the exact implications of this decision are. Importantly, the Brexit vote does not lead to any immediate legal consequences for existing IP rights, nor for the grant of new IP rights after 23 June 2016.
As of today, there are various scenarios conceivable concerning the consequences for Union trademarks once the UK notified the European Council of their intention to withdraw:
There is a chance that pre-existing Union trademarks can be converted within a reasonable deadline into national UK trademarks, so that that the complete protection remain unchanged but based on the national UK trademark. The EUIPO is already acquainted with the conversion of a national trademark into a Union trademark.
Likewise, Union trademarks continue to apply in the UK even after the Brexit but will be treated as national trade marks.
There is also the option of a re-filing of core trademarks in the UK as an International Registration (Madrider system).
It is also possible that after the Brexit, Union trademarks will remain unaffected. This scenario is highly unlikely considering that this is not compatible with the basic idea of the concept of the European Union.
It is difficult to assess the full impact that Brexit will have on the protection of Union trademarks rights in the UK. It remains to be seen what consequences will arise after the UK exit. To avoid a potential protection gap and for the purpose of monitoring conflicting trademarks, the UK should, already now be treated as any other European country outside the Union.
Cooley ALERT, Brexit and the European Trade Mark System, 24. Juni 2016,
Julius STOBBS/Lucy CUNDLIFFE, Brexit, Where next for EU trademarks?, World Trademark Review, 63/2016, 80
Anna CARBONI/Michael HAWINKS et al., How the Brexit Vote Will Affect Brand Owners: A Q&A Guide, (besucht am 14. 11.2016)