
The party criticizes that this creates barriers between Northern Ireland and the rest of the UK.
The protocol violates the Unification Act of 1800, in which Great Britain and Ireland were united – and the Good Friday Agreement of 1998, which ended the decades-long Northern Ireland conflict.

The background: After Brexit, Great Britain also left the EU internal market and the European customs union at the turn of the year. For Northern Ireland, a separate protocol was agreed in the Brexit Treaty to prevent border controls between Ireland and Northern Ireland – in order to counter the risk of a bloody conflict flaring up again.

The result: a goods border in the middle of the kingdom. This is exactly what the pro-British DUP is now opposed to.
EU vaccine blunder gives critics a boost
The dispute was exacerbated by a mistake by the EU Commission on the subject of corona vaccines: It had initially considered restricting vaccine exports to Northern Ireland due to the shortage. For this she wanted to use an exception rule of the Brexit protocol agreed with London. After massive protests from Great Britain and the EU member Ireland, Brussels quickly dropped the plan.
[ source link ]
https://www.spiegel.de/politik/ausland/nordirland-democratic-unionist-party-will-gegen-brexit-vertrag-klagen-a-7e5c677f-d63c-40ad-9848-d9d03bfecd36
Northern Ireland Democratic Unionist Party sue Brexit treaty