Last month, he pardoned another African-American heavyweight boxing champion, Jack Johnson, for racially motivated charges related to his relationship with a white woman in 1913. But Ali, a conscientious objector, had his conviction reversed by the U.S. Supreme Court four years later.
"I ain't got nothing against them Viet Cong", he told reporters. "This was all spontaneous and I think, as a lot of people like to say, impulsive".
Trump, like Ali, dodged the Vietnam War - a battle he famously compared to avoiding sexually transmitted diseases - but did so through legal means.
Well, Trump couldn't be too serious about pardoning the late boxer, who died in 2016.
Ali was also charged in 1967 with traffic violations - making an improper left turn and driving without a license - but Trump can pardon only federal crimes.
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Besides criticizing Trump for offering something unnecessary, Sharpton said Trump's past "anti-Muslim and Islamophobic policies and rhetoric" were an affront to Ali's religion.
Following the good deed, Trump announced plans for other presidential pardons on Friday.
Trump has also floated a possible pardon for TV personality Martha Stewart and potentially commuting the sentence of former IL governor Rod Blagojevich, who was convicted on corruption charges in 2011.
"No, I am not going ten thousand miles from home to help murder and burn another poor nation simply to continue the domination of white slave masters of the darker people the world over". Although Trump is reportedly very into pardoning now, especially for celebrities and those with celebrity champions, naming Ali raised eyebrows.