Northern Ireland lawmakers on Tuesday voted in favour of continuing key parts of post-Brexit trade rules for the region, but opposition from pro-British unionist politicians triggered an independent review into the arrangements.

Northern Ireland lawmakers voted to continue applying post-Brexit rules, but opposition from unionist parties underscored the challenge facing the UK government as it tries to maintain political stability in the region.

Northern Ireland will remain subject to EU rules for at least four more years after Stormont voted to continue post-Brexit trading arrangements in the region. Every unionist in the Assembly voted against the Windsor Framework in the first ever consent vote on the arrangements but they were outvoted by nationalists and non-aligned members.

Irish nationalists and neutrals overpower Stormont’s British unionist minority in a bitterly disputed ‘consent’ test provided by the U.K.’s withdrawal treaty with the EU.

Stormont assembly members have begun debating whether to continue with Northern Ireland's post-Brexit trading arrangements. The process, known as the democratic consent motion, was first agreed between the UK and EU in the 2020 Withdrawal Agreement to give local politicians a say in the new post-Brexit trading rules.

Rules will continue to serve as a means of maintaining an invisible Border on the island for further four years

Some small British businesses have stopped selling their products to the EU and Northern Ireland as a result of new “complex” rules coming into effect next week – something they say is a “barrier” to growth. The EU’s General Product Safety Regulation (GPSR) will apply as of 13 December and have been put in place to upgrade product safety standards.

The process to trigger the vote began at the end of October when Northern Secretary Hilary Benn sent a letter to the Speaker Edwin Poots asking First Minister Michelle O’Neill and Deputy First Minister Emma Little-Pengelly to table a motion by the end of November.