Yes, he can, from Andrew Napolitano at lewrockwell.com:
Most presidential pardons — indeed all pardons that President Donald Trump has issued — have been for specific crimes of which the subject of the pardon has already been charged and convicted. Yet, Trump, never one to be restrained by precedent, has let it be hinted that he might issue prophylactic pardons to relatives and colleagues who have neither been convicted nor charged with any crimes. And he might pardon himself. Can he do that?
The short answer is yes. Here is the backstory.
The pardoning power is expressly and exclusively granted to the president in the Constitution. Article Two, Section 2, Clause 1, states that the president “shall have Power to grant Reprieves and Pardons for Offenses against the United States, except in cases of impeachment.” When unpacked, that broad language reveals that the president can only pardon for federal crimes, not for anyone’s impeachment, and he does not need the approval of anyone else in the government.
Trump is the subject of a criminal investigation in New York City for alleged or potential violations of state laws. But the existence of a state criminal probe of the president does not impair his ability to insulate himself from the legal consequences of a federal criminal probe, since it is clear that the president cannot pardon anyone — including himself — for state offenses.
It’s a shame that the only decent Democrat is dropping out of politics. It would be interesting to find out why. From RT at rt.com:
Outgoing Democratic Rep. Tulsi Gabbard has urged President Donald Trump to issue pardons for Edward Snowden and Julian Assange, echoing growing calls to absolve whistleblowers who helped to “expose” the US “deep state.”
“Since you’re giving pardons to people, please consider pardoning those who, at great personal sacrifice, exposed the deception and criminality of those in the deep state,” Gabbard said in a tweet addressed to the president on Thursday, referring to Snowden and Assange.
The request comes less than a day after Trump granted a pardon for former national security adviser Michael Flynn. His case became a central plank in the Trump-Russia “collusion” narrative after he was accused of misleading investigators about contacts with a Russian diplomat following Trump’s election win in 2016. While the Justice Department moved to have the case thrown out, citing misconduct in the FBI’s probe, a federal judge resisted that effort, prompting the president to intervene on Wednesday.
Gabbard, who’s set to leave office at the end of her congressional term, previously introduced a resolution alongside GOP lawmaker Matt Gaetz (Florida) urging the government to drop its charges against Snowden – who was indicted under the World War I-era Espionage Act for his role in leaking classified material revealing illegal mass surveillance by the National Security Agency (NSA). Though the antiquated law was originally intended to prosecute foreign spies, it has been repeatedly wielded against journalists and whistleblowers.