The Pains and Penalties Bill 1820 was a bill introduced to the British Parliament in 1820, at the request of King George IV, which aimed to dissolve his marriage to Caroline of Brunswick, and deprive her of the title of queen.

George and Caroline had married in 1795, when George was still Prince of Wales. After the birth of their only child, Princess Charlotte of Wales, they separated. Caroline eventually went to live abroad, where she appointed Bartolomeo Pergami to her household as a courier. He eventually rose to become the head servant of her household, and it was widely rumoured that they were lovers.

In 1820, George ascended the throne and Caroline travelled to London to assert her rights as queen of Great Britain and Ireland. George despised her and was adamant that he wanted a divorce. Under English law, however, divorce was not then possible unless one of the parties was guilty of adultery. As neither he nor Caroline would admit to adultery, George had a bill introduced to Parliament, which if passed would declare Caroline to have committed adultery and grant the King a divorce. In essence, the reading of the bill was a public trial of the Queen, with the members of the House of Lords acting as judge and jury.

After a sensational debate in the Lords, which was heavily reported in the press in salacious detail, the bill was narrowly passed by the upper house. However, because the margin was so slim and public unrest over the bill was significant, the government withdrew the bill before it was debated by the House of Commons, as the likelihood of it ever passing there was remote.