He’s also said he’d intervene in the case of a Chinese businesswoman arrested in Canada if it got him a better trade deal.
And he repeatedly comments on the ongoing investigation into Russian meddling and collusion with his 2016 presidential campaign team, most recently calling his former lawyer who co-operated with the investigation, a rat.
While legal experts say Trump may not have the direct power to intervene in cases, when politicians comment on legal proceedings, it has the potential to set off appeals and other complications.
That can impede the impartiality of the case.
The right to a fair trial is important to both Canadian and American justice systems, explained Rob De Luca, the director of the democracy and the rule of law program at the Canadian Civil Liberties Association.
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He said it’s important to “allow that process full autonomy.”
“The problem with political interference – whether it be at the appeals stage or while the case is live – is that it can introduce a number of considerations that have nothing to do with giving a person their proper day in court,” he said. “[It] can be for completely ulterior motives.”
Former justice minister Peter MacKay told Global News he’s worried about an apparent upward trend in politicians commenting on cases.
“This impenetrable wall that used to exist between the world of politics — the executive branch — and the judiciary … that wall appears to be crumbling, rapidly,” he said.
An army statement on Friday, Dec. 14, said Major Mathew Golsteyn was charged with killing an Afghan man during Golsteyn’s 2010 deployment to Afghanistan.
Golsteyn was leading a team of Army Special Forces troops at the time.
He admitted to killing the man because he believed that the bombmaker was responsible for an explosion that killed two U.S. Marines.
Trump wrote on Twitter on Sunday that he would be reviewing the case, calling Golsteyn a “military hero.”
In a statement on Sunday, Army Col. Rob Manning, a Pentagon spokesman, said Trump and the Department of Defense should not interfere in matters of military law enforcement.
“The allegations against Major Matt Golsteyn are a law enforcement matter. The Department of Defense will respect the integrity of this process and provide updates when appropriate,” the statement read.
Trump does have the power to pardon people, but some military legal experts say the president’s tweet could potentially violate the uniformed code of military justice.
“The UCMJ (Uniform Code of Military Justice) has an explicit prohibition on the exercise of unlawful command influence by any convening authority, a term that incidentally includes the president of the United States,” law professor Eugene Fidell told Reuters.
For her part, the wife of Golsteyn welcomes the president’s scrutiny, saying she wants “whatever it takes to have justice for Matt.”
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Prominent Chinese businesswoman Meng Wanzhou was arrested in Canada but faces extradition to the U.S. to face charges relating to violating sanctions on Iran.
The U.S. is currently embroiled in a trade spat with China – and Trump has said he could leverage the case if necessary to secure a good deal.
“If I think it’s good for the country, if I think it’s good for what will be certainly the largest trade deal ever made – which is a very important thing – what’s good for national security – I would certainly intervene if I thought it was necessary,” Trump said in a wide-ranging interview with Reuters in the Oval Office last week.
Canada has maintained that the arrest of Meng was not political and that the rule of law is a fundamental Canadian principle.
“That is one of the core foundations of everything that’s great about our country, one of the core foundations of our democracy,” Chrystia Freeland told The Canadian Press on Monday.
Trump’s comment could infringe on Meng’s Charter right to due process, de Luca explained.
“Is there a due process argument if we allow her to be moved to the U.S.? I don’t know the answer to that.”
“But she does have the right to raise Charter concerns in her hearing.”
“It’s certainly going to be argued,” MacKay agreed. “The defence now have a hook that they can use to suggest that the comments of President Trump have politicized this.”
MacKay also said Prime Minister Justin Trudeau’s comments that he knew about the case before Meng was arrested could also play into an argument about the political aspects of the case.
Trump has also slammed the FBI repeatedly for investigating collusion between Russia and his 2016 presidential campaign staff. He has said the FBI was “breaking in” to his former lawyer Michael Cohen’s office, when they had a court-approved warrant, and called Cohen a rat after he co-operated with the Justice Department.
Former FBI director James Comey, who was fired under Trump, said it was a pattern of Trump’s to undermine the system – and called for others to stand up to Trump.
“This is the president of the United States calling a witness, who has co-operated with his own Justice Department a rat,” Comey said. “We have to stop being numb to it; whether you’re Republican or Democrat, stand on your feet, overcome your shame and say something.”
“The FBI’s reputation has taken a big hit because the president of the United States has lied about it constantly.”
MacKay said it’s a “necessity” to not interfere with the process because it will “bring the whole rule of law into disrepute.”
“It undermines public confidence,” Mackay said, “and it becomes part of the broader narrative that people are cynical about the justice system.”
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The U.S. isn’t alone in commenting on legal cases.
On Monday, Crown prosecutors in Ottawa had to defend against an argument of political interference in the case against Vice-Admiral Mark Norman.
Before charges were laid, Trudeau commented that he expected the case to go before the courts, which Norman’s defence lawyers said could have influenced Crown lawyers.
MacKay also pointed to the Gerald Stanley case – where Trudeau and current Justice Minister Jody Wilson-Raybould both commented that the justice system in Canada needed to “do better” after the not-guilty verdict was announced.
MacKay, a lawyer and politician, said he understands the urge to comment on cases, but that politicians should refrain.
“I do understand the natural inclination of politicians to want to comment on topical public policy matters but they have to refrain and show discipline,” he said.
“That’s a very slippery slope that we appear to be on, currently.”
*with files from the Associated Press
© 2018 Global News, a division of Corus Entertainment Inc.