Final answer:
Abraham Lincoln outlawed convict labor slavery in 1865.
Step-by-step explanation:
The US president who outlawed convict labor slavery was Abraham Lincoln in 1865. He issued the Emancipation Proclamation in 1863, declaring that all slaves in rebel states were to be set free. Then, with the ratification of the Thirteenth Amendment to the United States Constitution in 1865, slavery and involuntary servitude, except as punishment for a crime, were officially abolished.
Learn more about Outlawing convict labor slavery in the US