In a media blitz Wednesday night and Thursday, U.S. President Donald Trump's lawyer Rudolph Giuliani told Fox and CNN he had received assurances that Special Counsel Robert Mueller will not indict the president while he is in office.

Whether a sitting president can be subjected to prosecution has never been tested at the U.S. Supreme Court, but Giuliani said Mueller's team agrees it is bound by a U.S. Justice Department memo from October 2000. That memo concluded U.S. presidents cannot be indicted because the prosecution would interfere with their ability to execute their constitutional duties.

That is not all Giuliani said, though. He told Fox News Thursday morning not just that the special counsel cannot indict President Trump but that Mueller's team cannot even subpoena the president to appear before a grand jury. Giuliani's theory is that if the president cannot be prosecuted, he cannot be called to testify in an investigation of his conduct.