That is the only way to describe Boris Johnson's request to suspend the UK parliament to prevent it from voting on Brexit (or voting him out of office). The UK parliament is the sole source of democratic legitimacy for that country's government. For the executive to purport to suspend it, nakedly to prevent debate, calls its right to govern into fundamental question.
Brexit has now become a full-blown constitutional crisis. There are already calls to protest in the UK. MPs are saying they will simply occupy the chamber and that the police will have to drag them out. Last time anything like this happened in the UK, that country got a civil war and the tyrannical executive lost their head. Hopefully it won't come to that. But the fact that this has even been tried underlines how urgently the UK needs democratic reform, to make it impossible.