a major grievance of southern slave owning states, leading up to the American Revolution in 1776. The 1790 United States Census recorded 694,280 slaves (17.8 per cent) of a total 3,893,635 population. After independence, the British Empire halted the Atlantic slave trade in 1807, and abolished slavery in its own territories, by paying off slave owners in 1833. In the US, northern states progressively abolished slavery. However, southern states did not. In Dred Scott v Sandford the Supreme Court held the federal government could not regulate slavery, and also that people who were slaves had no legal rights in court. The American Civil War was the result. President Lincoln's Emancipation Proclamation in 1863 made abolition of slavery a war aim, and the Thirteenth Amendment of 1865 enshrined the abolition of most forms of slavery in the Constitution. Former slave owners were further prevented from holding people in involuntary servitude for debt by the Peonage Act of 1867. In 1868, the Fourteenth Amendment ensured equal access to justice, and the Fifteenth Amendment required that everyone would have the right to vote. The Civil Rights Act of 1875 was also meant to ensure equality in access to housing and transport, but in the Civil Rights Cases, the Supreme Court found it was "unconstitutional", ensuring that racial segregation would continue. In dissent, Harlan J said the majority was leaving people "practically at the mercy of corporations". Even if people were formally free, they remained factually dependent on property owners for work, income and basic services. Like slavery, common law repression of labor unions was slow to be undone. In 1806, Commonwealth v Pullis held that a Philadelphia shoemakers union striking for higher wages was an illegal "conspiracy", even though corporations—combinations of employers—were lawful. Unions still formed and acted. The first federation of unions, the National Trades Union was established in 1834 to achieve a 10 hour working day, but it did not survive the soaring unemployment from the financial Panic of 1837. In 1842, Commonwealth v Hunt, held that Pullis was wrong, after the Boston Journeymen Bootmakers' Society struck for higher wages. The first instance judge said unions would "render property insecure, and make it the spoil of the multitude, would annihilate property, and involve society in a common ruin". But in the Massachusetts Supreme Judicial Court, Shaw CJ held people "are free to work for whom they please, or not to work,