Despite the actions of abolitionists, free blacks were subject to racial segregation in the Northern states. While the United Kingdom did not ban slavery throughout most of the empire, including British North America till 1833, free blacks found refugee in the Canadas after the America Revolution and again after the War of 1812. Refugees from slavery fled the South across the Ohio River to the North via the Underground Railroad. Midwestern state governments asserted States Rights arguments to refuse federal jurisdiction over fugitives. Some juries exercised their right of jury nullification and refused to convict those indicted under the Fugitive Slave Act of 1850.