Yates, who was the USA’s top law enforcement official, told justice department lawyers not to defend Trump’s 90-day ban on people from seven Muslim-majority countries entering the US.
She said she wasn’t sure the ban was consistent with the department’s obligation to ‘Stand for what is right’.
The White House said Yates ‘betrayed the department by refusing to enforce the order'.
If you were to look back to 2015, you'd find footage of Jeff Sessions (Donald Trump's new Attorney General) pressing Yates about the need for the nation's top lawyer to keep independence from the White House.
Jeff Sessions is shown in the 2015 footage questioning Ms Yates on whether she would “say no” and continue to give impartial legal advice if the President asked for “something improper”.
“You have to watch out because people will be asking you to do things, you just need to say no about,“ he said, asking: “You think the Attorney General has a responsibility to say no to the President if he asks for something that’s improper?”
“A lot of people have defended the [Loretta] Lynch nomination, for example, by saying: ‘[Obama] appoints somebody who’s going to execute his views, what’s wrong with that?’
“But if the views a president wants to execute are unlawful, should the Attorney General or the Deputy Attorney General say no?
In response, Ms Yates said: “I believe that the Attorney General or the Deputy Attorney General has an obligation to follow the law and the constitution and to give their independent legal advice to the president.”
Critics have taken to social media to claim Mr Sessions' sustained questioning proves the Trump administration was hypocritical to fire Ms Yates.
In her letter to justice department lawyers, the acting Attorney General said: “I am responsible for ensuring that the positions we take in court remain consistent with this institution’s solemn obligation to always seek justice and stand for what is right.
“At present I am not convinced that the defence of the executive order is consistent with these responsibilities nor am I convinced that the executive order is lawful.”