President Trump announced on Thursday that he would posthumously pardon Jack Johnson, the first black heavyweight boxing champion. Johnson was arrested in 1912 for driving his white girlfriend over state lines. Prosecutors said it violated the Mann Act, which prohibited crossing state borders with a woman for "immoral purposes." The case is now often seen as emblematic of racism entrenched in the U.S. justice system. Johnson died in 1946. His pardoning marks the third-ever posthumous pardon in U.S. history.

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