A US federal judge on Tuesday ruled that White House staff can be made to testify before Congress, rejecting the Trump administration’s claims of immunity.

The ruling specifically compels former White House counsel, Don McGahn to testify to an inquiry into Russian interference in the 2016 United States election.

The Department of Justice however says it will appeal the ruling which also has major implications for the Democrats-led impeachment inquiry against Trump.

The Trump administration has refused to cooperate with the impeachment inquiry and other Democrats-led investigations, directing current and former White House officials to defy subpoenas for testimony and documents.

Mr. McGahn, who left his post in October 2018 was summoned to appear before the House Judiciary Committee in May to answer questions about the alleged attempts by Trump to impede the now concluded Mueller investigation into Russian involvement in the 2016 presidential election.

In her ruling, US District Judge Ketanji Brown Jackson said that ‘no one is above the law’.

“Executive branch officials are not absolutely immune from compulsory congressional process – no matter how many times the executive branch has asserted as much over the years even if the president expressly directs such officials’ noncompliance,” she wrote.

Judge Jackson also explicitly said the president does not have the power to stop his aides from responding to subpoenas from Congress, adding that ‘presidents are not kings’,

She however did say that Mr. McGahn could invoke executive privilege ‘where appropriate’ to protect potentially sensitive information.