Sally Yates was named deputy attorney general by then-President Barack Obama in 2015. Mr Trump asked her to stay on as acting head of the Justice Department. Hours after Ms Yates said the executive order did not appear to be lawful, President Donald Trump replaced her.
Mr Boente has since been sworn in and issued a statement instructing Justice Department lawyers to defend the president's order.
Dana Boente wrote:
''Based upon the office of the of Legal Counsel's analysis, which found the Executive Order both lawful on its force and properly drafted, I rescind former Acting Attorney General Q. Yates January 30, 2017 guidance and direct the men and women of the Department of Justice to do our sworn duty and to defend the lawful orders of our President'