Roberts, as the head of the federal judiciary, has been facing mounting pressure to protect the courts from political interference. With a lifetime appointment, it remains to be seen whether the 70-year-old Chief Justice will take further steps to defend judicial independence as Trump continues his broadsides against the judiciary.

"For more than two centuries," Chief Justice John Roberts said on Tuesday, "it has been established that impeachment is not an appropriate response to disagreement concerning a judicial decision. The normal appellate review process exists for that purpose.