A pardon wipes the slate clean for someone convicted of a crime, but a commutation only lets someone out of a prison sooner, said Robert Spitzer, former president of the Presidency Research Group of the American Political Science Association.
Lewis "Scooter" Libby, former chief of staff for Vice President Cheney, convicted on perjury and obstruction of justice in Central Intelligence Agency leak case disclosing identity of Central Intelligence Agency officer Valerie Plame Wilson, was pardoned in April.
Blagojevich, by contrast, is now serving a 14-year prison sentence after having been found guilty in 2011 on public corruption charges.
New York Attorney General Barbara Underwood on Thursday criticized Trump's pardons of his supporters and called on the state Legislature to change the state's double-jeopardy law so that those who break its laws can not evade justice with a presidential pardon. Beneficiaries include controversial Arizona sheriff Joe Arpaio, who had been convicted of criminal contempt of a court, and Scooter Lobby, a George W Bush White House staffer convicted in 2007 of leaking the identity of an undercover Central Intelligence Agency officer. D'Souza, who spent eight months in a halfway house in San Diego, said he was grateful he is no longer labeled a felon and can vote again.
"Trump's Dinesh D'Souza pardon today, on top of his pardons of Scooter Libby and Joe Arpaio, make sense only as an elephant-whistle to Michael Cohen & all who know damning things about Trump: protect me & I'll have your back".
President Donald Trump said that he would give a full pardon to Dinesh D'Souza, the political commentator, author, and filmmaker who plead guilty in 2014 to a felony campaign finance violation. Stewart's case has frequently been cited as an example prosecutors can use to bring charges for failing to be candid with federal investigators.
Stewart and Blagojevich both were involved with Trump's "Apprentice" reality TV television show.
I'll tell you another one - there is another one I'm thinking about.
Trump granted the reprieve to D'Souza, who pleaded guilty to exceeding campaign donation limits in contributing to a long-shot Republican Senate candidate in NY.
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D'Souza was convicted of making an illegal campaign contribution in 2014.
Stewart was convicted in 2004 of obstructing justice and lying to the government about why she unloaded stock just before the price plummeted. "The career prosecutors and agents did their job".
"The president said, 'Dinesh, you've been a great voice for freedom, ' and he said that, 'I got to tell you man-to-man, you've been screwed", D'Souza told Fox.
He, like Arpaio and Trump, for years trafficked in the racially charged "birther" lie that former president Barack Obama was not born in the United States and was therefore ineligible to serve in the White House.
D'Souza retweeted Mr Trump's tweet but did not comment otherwise.
D'Souza has nettled the left with films such as "Hillary's America: The Secret History of the Democratic Party" and "2016: Obama's America".
"What he did does not justify 18 years in jail", Trump said.
Donald Trump pardoned a firebrand conservative author on Thursday and signalled that similar clemency could be on the way for lifestyle guru Martha Stewart, the latest in a series of controversial pardons by the U.S. president.
Most recently, he apologized for a tweet taunting survivors of the shooting in Parkland, Fla., after Florida lawmakers opted not to ban assault weapons. "Then he got fired & I got pardoned", Mr. D'Souza said.
The tweets have been sharply criticized by some Florida Republicans, including Gov. Rick Scott. He was also convicted of trying to exchange an appointment to the U.S. Senate seat for campaign cash.