Because it appears that is more or less what happened to start the Iraq war.
The defector Rafid Ahmed Alwan al-Janabi, also known as Curveball, has admitted telling lies to the German and USA Secret Services about Iraq having WMD in an attempt to bring down Saddam Hussein's regime in Iraq.
The details he provided were the main basis of Colin Powell's speech to the United Nations with the result being the invasion of Iraq. Rafid is now claiming that his lies could have been discredited fairly easily, indeed Donald Rumsfeld's memoirs admit that Saddam had no weapons of mass destruction.
But the question is: did he do the right thing?
His lies started a war lasting several years resulting in hundreds of thousands of deaths and a destabilised region but led to the overthrowing of a tyrant and possibly bringing some form of democracy and freedom to the country.
More on the story here.