5th of Feb 1705 (thread)
The Alien Act declared that Scottish nationals in England were to be treated as aliens and any estates held by Scots would be treated as alien property which would hinder inheritance. It also included restrictions on the imports of Scottish merchandise..

around half of Scotland's total trade including cattle, linens and coal. There was also a ban on the export of arms and ammunition to Scotland to prevent the Scots from raising an army to invade England....

All this was enacted to pressurise the Scots to form a Union and in fact the act contained a clause that it would be suspended if Scotland entered into negotiations regarding the proposed Union of a parliaments by 25th of December 1705....

The Act along with bribery of many within the Scottish Parliament achieved its goal and the Scots agreed to The Act of Union which commenced on 1st of May 1707