What happened? 
On 3 March, the EU announced that the ‘unilateral decision’ of the United Kingdom on Trade Rules is a breach of international law and threatened legal action. During Westminster’s annual budget, the UK announced its decision to unilaterally extend the grace period on the checks for goods moving between Britain and Northern Ireland, which is a violation of the Northern Ireland Protocol. 

On 2 March, Michel Barnier stepped down as the EU's chief Brexit negotiator and his specialist team of eurocrats have been disbanded. Barnier warned that there remain "many challenges ahead" for the EU and UK. 

What is the background?
First, the unilateral decision by the UK and the apparent breach of international law over the Northern Ireland Protocol. As the tensions between the two sides escalated, the European Commission Vice President said that the British decision to take unilateral action on trade rules relating to Northern Ireland marks the second time it has declared its intention to breaching international law. The UK had previously asked for the deadline to be extended until 2023, but the EU had not agreed to it. The UK government's decision indicates that it will waive customs paperwork on food entering Northern Ireland until October. This is beyond the 1 April deadline it had previously agreed with the EU. In September 2020, the UK had considered breaking the terms of the Brexit divorce agreement relating to Northern Ireland, only to back down. Both cases give the EU leverage to start legal proceedings through the terms of the protocol. 

Second, new issues vis-a-vis Northern Ireland. With the decision to keep the land borders free of checkpoints, they hoped to prevent additional troubles between the UK and Northern Ireland. This came with a price; that is, the goods arriving from the rest of the UK would be subject to checks and extra paperwork as they cross the Irish Sea. Many members of PM Johnson’s party and Unionist politicians in Northern Ireland believe that the deal treats the region differently from the rest of the UK. On 2 March, Ireland Democratic Unionist Party’s agriculture minister ordered officials to halt work on permanent border control posts. In January 2021, the EU  triggered an override clause in the Northern Ireland Agreement, to secure vaccine supplies. This unilateral decision was taken without consulting in London or Dublin.

Third, emerging EU-UK complexities from the two months of the new arrangements. When the deal was signed in December 2020, many issues were given a grace period to ensure the proper measures are in place. For example, the immediate impact was felt with the fisheries sector and the lorry workers who would transport goods across the borders. Both complained of longer paperwork and processing time. Late January also witnessed the EU taking export control measures to deal with the imbalance in the vaccine procurement and administering strategy of the UK. Following this, new issues relating to the banking and financial sectors have emerged. This way, political and legal obligations have propped up many times during the past months. 

What does it mean?
Though the EU and UK were expected to face short-term losses and logistical challenges, Northern Ireland seems to face the substantial brunt of the post-Brexit trade deal. 
Second, the new trade deal disputes over border protocols have wreaked havoc among the already fragile arrangements that exist between them. The unilateral decision would necessarily ease the impact of the Brexit on the businesses in Northern Ireland but comes in the way of “the proper implementation,” of the Brexit deal.