I was enthusiastically in favour of "remain". Since the disastrous referendum result, I have thought long and hard about whether there could be any benefit at all in leaving, as far as intellectual property is concerned. I have come up with nothing, but the downsides are clear.
First, the one piece of not-so-bad news. The European patent system will be largely unaffected. The European Patent Convention is not an EU treaty, and there are many member states that are not EU members.
There are some cases where additional costs will be incurred upon grant of a European patent. EPC member states will be able to insist upon UK patent proprietors appointing a local representative, which they cannot do at present. This would typically add between £100 and £200 per country, if it happens.
Should the Unitary patent system, which allows for grant of a single patent to cover all EU member states, ever come into effect, I will be able to represent UK-based clients in the European Patent Office to get such patents granted, even though they will not have direct legal effect in the UK.
EU Trade Marks and Designs
On Exit Day (at the end of the transition period) every existing EU trade mark and design registration will create a clone UK national equivalent. This is automatic. When the registration comes up for renewal, the UK will have to be renewed separately from the EU registration. Thus, not being in the EU means you have to pay more (up to 50% more for designs) to renew than if the UK were still in the EU.
Unregistered Design Right
This is a real mare's nest that I am not sure anyone has got to the bottom of yet! The EU and UK unregistered design right systems were carefully set-up to coexist within the EU, and pulling them apart causes major problems. The geographical location of first marketing is central to these rights. It seems like you will have to choose between either having UK design right, by first marketing in the UK, (with no EU protection), or EU unregistered design right by first marketing in the EU (but with no UK protection).
Heads You Loose, Tails You Loose
As far as IP is concerned, leaving the EU is only a matter of increased cost and loss of rights - there is no gain. In some cases, losses can be mitigated by additional payment, but for designs, there is no way out that I can see - it is simply rights lost for UK businesses.