The Westminster system has proven its utter failure to provide any measure of accountability for its executive when it emerged that the person who gets to decide whether Boris Johnson violated the Ministerial Code is one... Boris Johnson.

US Presidents have been impeached, and in the case of Nixon forced to resign. French Presidents, probably the most powerful executives in the West, have been successfully prosecuted for crimes committed in office. Same with Helmut Kohl, the King of Spain, or Italian Prime Ministers. British Prime Ministers get a free ride for war crimes like Tony Blair or gross corruption like Boris Johnson.