A Belfast judge tossed a lawsuit challenging the Northern Ireland Brexit protocol in a boost for U.K. and European Union negotiators just hours before they’re set to announce new arrangements on goods checks across the Irish Sea.

Judge Adrian Colton ruled Wednesday that post-Brexit trading agreements concerning Northern Ireland are lawful even though they conflict with the 1800 Acts of Union.

The protocol created border checks in the Irish sea as a way to ease regulatory disputes between the U.K. and EU over goods entering the Republic of Ireland in the wake of Brexit, in a bid to avoid checks on the land border between Northern Ireland and the Republic which has long been a flash-point for sectarian violence.

Campaigners including former Northern Ireland First Minister Arlene Foster contended that the protocol was incompatible with the U.K.’s constitution under the Acts of Union.

“The key finding in today’s court ruling that the protocol has repealed a key plank of the Acts of Union is a wake up call to every unionist,” Jim Allister, a unionist politician in Northern Ireland and lead claimant in the case, said in a statement. “It is now confirmed the protocol is dismantling the Union.”

An agreement between the EU and U.K. is expected today to extend the grace period for post-Brexit trading rules in Northern Ireland. Under current arrangements the sale of chilled meats and fresh sausages into Northern Ireland from the rest of the U.K. is due to be banned at the end of June.