A federal court has ruled that White House aides can be required to testify before Congress as the impeachment inquiry against US President Donald Trump reaches its final stages.
The Trump administration had previously claimed that Trump's top aides have absolute immunity against any court.
US appeals court judge Ketanji Brown Jackson rejected the Trump administration's claims of immunity against the law, insisting on Monday that "no one is above the law".
"No one, not even the head of the Executive branch, is above the law," Judge Jackson said, adding that "presidents are not kings".
In her court order, Judge Jackson ordered former White House counsel Don McGahn, who defied a Congress subpoena, to appear in court to testify.
"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 noted.
The judge added that her order had broad application to current and former White House officials, as well.
The court order has major implications for the Democrat-led impeachment inquiry against Trump.
Trump's top aides, including former national security advisor John Bolton, White House Chief of Staff Mick Mulvaney and Secretary of State Mike Pompeo, could be required to come testify for the impeachment.
The administration's justice department said it will appeal the ruling.
The impeachment inquiry was launched in September over Trump’s alleged pressure on Ukraine to investigate his presidential rival Joe Biden.
The Trump administration has ordered current and former White House officials not to co-operate with the impeachment inquiry and other Democrat-led investigations, directing them to defy subpoenas for testimony and documents.