Barnaby Joyce, the deputy prime-minister of Australia, occasional beetroot impressionist and the man who threatened to kill Johnny Depp’s dogs has been ruled ineligible to be an MP by the High Court https://www.theguardian.com/australia-news/live/2017/oct/27/politics-live-high-court-citizenship-joyce
For earlier coverage see here https://camestrosfelapton.wordpress.com/2017/08/14/stealth-kiwis-takeover/
The short version being, a senator of the Green Party resigned from the senate because she discovered she was accidentally a Canadian and the Australian Constitution requires MPs and Senators to have no ties to another nation. Shortly after another Green senator resigned for similar reason. The Green Party was much mocked for this. However, it then emerged various other MPs/Senators may have had various levels of eligibility for citizenship. This created a kind of domino effect constitutional crisis which ended up in the High Court. The biggest name being Barnaby Joyce a man who has traded off a fare-dinkum Aussie country bloke image for his whole career but who was (inadvertently) eligible to be a Kiwi.
The Green Party haven’t quite brought down a government but they’ve come pretty close, just by being nice and following the rules.