I've noticed that it's commonplace for leaders to just switch language in the middle of their sentience, is there some equal language speaking rule?
No, that's common for all bi-lingual politicians in Canada -- especially during debates in the House of Commons.
I have read a biography of Sir Wilfrid Laurier, which from memory mentioned that in the 19th century the House of Commons had a rule against switching between the French and English languages in mid-speech. It was with reference to a bi-lingual politician who, after being interrupted, continued his remarks in the other language than the one he had been using previously.
