The US government has come close; none of it was "proper" court-backed bans though. Wikileaks remains a legal organisation in the US, albeit one that has been claimed to be illegal by several politicians and that has been treated as an enemy by various US intelligence organisations.
One might argue that argue that those actions were undemocratic in themselves (repeated harassment of Wikileaks activists at the US border; pressure on payment providers to withhold donations; increased targeting of Wikileaks sympathisers for excessive illegal surveillance