President Donald Trump granted a full, posthumous pardon for Jack Johnson, the first black heavyweight boxing champion, who was convicted of racially tinged federal morals charges more than a century ago.

Trump signed a full posthumous pardon for Johnson while flanked by boxing royalty including Lennox Lewis, Deontay Wilder and Rocky himself, actor Sylvester Stallone.

"I am taking this very righteous step, I believe, to correct a wrong that occurred in our history and honor a truly legendary boxing athlete," Trump told his guests. "Jack Johnson was not treated fairly and we have corrected that."

Johnson was convicted under a law that prohibited the transport of women over state lines, called the Mann Act. The law was sometimes employed by racist authorities to punish black men who had relationships with white women; it was later amended to apply only to the transport of women for purposes of prostitution or illegal sex acts.

Johnson's case has been derided for decades as shaky and motivated by racial animus toward the boxer, who defeated white opponents in the ring and enjoyed relationships with white women out of it.