Where? Singapore? It's not illegal per se, but public criticism (not private; I know many civil servants who'll be happy to criticise some of our government's execution in person) is highly discouraged if they value a career in the civil service or any of the many organisations the PAP has their tentacles in.

when I was doing study abroad in Singapore, there was a class on corruption in south east Asian governments. However, they were not allowed to discuss Singapore in that class.