The Caroline affair diplomatic crisis, beginning in 1837 involving the United States, Britain, and the Canadian independence movement, was defused by the negotiations that led to the Webster-Ashburton Treaty in 1842, which led to the legal principle of the "Caroline test".
The Caroline affair (also known as the Caroline case) was a diplomatic crisis beginning in 1837 involving the United States, Britain, and the Canadian independence movement. The diplomatic crisis was defused by the negotiations that led to the Webster-Ashburton Treaty in 1842, in which both the U.S. and Britain admitted to wrongdoing. In the aftermath, the incident led to the legal principle of the "Caroline test". 
