The Acts of Union were twin Acts of Parliament passed in 1707 (taking effect on 26 March) in the Scottish and the English Parliaments. The effect was twofold:
- to create a new Kingdom of Great Britain, though the name had been used on occasion since 1604 when speaking of the Kingdoms of England and Scotland together. Up to this time, England and Scotland had been separate Kingdoms, although since 1603 had shared the same monarch. Wales was also part of this Great Britain since it had been absorbed by England by the Acts of Union 1536-1543.
- to dissolve both parliaments and replace them with a new Parliament of the Kingdom of Great Britain. (Although the new parliament was to be based in the former home of the English parliament.)
While there had been three earlier attempts to unite the two countries by Acts of Parliament, these were the first Acts which had the will of both political establishments behind them, albeit for rather different reasons. In the English case, the purpose was to establish the Royal succession along Protestant lines in the same manner as provided for by the English Act of Settlement 1701 rather than that of the Scottish Act of Security. In the Scottish case, the purpose was partly to use English subsidies to recover from the financial problems caused by the failure of the Darién scheme and partly to remove English trade sanctions put in place through the Alien Act to force the Scottish Parliament into compliance with the Act of Settlement.
The Acts of Union were not universally popular in Scotland, particularly amongst the general population. Many petitions were sent to the Scottish Parliament against union, and there were massive protests in Edinburgh on the day it was signed. Many historians have since argued that the Scots Parliamentarians were coerced into signing up for union by English bribery.
The Act incorporated provisions for Scotland to send representative peers from the Peerage of Scotland to sit in the House of Lords. It guaranteed that the Church of Scotland would remain the established church in Scotland, and that the Court of Session would remain. It also established that the flag of Great Britain would be based on the Flag of England and Flag of Scotland; the exact design of the Flag of Great Britain was adopted later.
Other provisions included to restate the Act of Settlement 1701 and the ban on Roman Catholics from taking the throne. It created a customs union and monetary union.
The treaty provided that if any 'laws and statutes' were 'contrary to or inconsistent with the terms' of the Treaty; that they would be null and void. This has not been held to prevent the Parliament of the United Kingdom from amending the Act.
Wales was considered to be part of England under the act.