The Clarity Act ( known as Bill C-20 before it became law ) was a law passed by Canadian Government in 1999 . The Clarity Act ( known as Bill C-20 before it became law ) is legislation passed by the Parliament of Canada that established the conditions under which the Government of Canada would enter into negotiations that might lead to secession following such a vote by one of the provinces . The Clarity Bill ( C-20 ) was tabled for first reading in the House of Commons on December 13 , 1999 .