Christchurch shooting is a good example, because the follow-up crackdown on associated content showed just how far this can go. Remember his "manifesto"? In NZ, its distribution was banned outright by law (or rather government order, but they have laws on the books that allow for it). Not so in Australia - they couldn't find any legal means to restrict it, so the government basically informally asked the ISPs to "do something".
And they did - to the point where a bunch of websites with forums were blocked outright because of their hands-off policy wrt comments (usually in some particular subforum; it's a fairly common way to keep it civil elsewhere) meant that there were a bunch of posts with links to the document.
The end result is that a bunch of completely unrelated stuff was blocked in Australia outright for a while, by private companies in charge of communications acting in unison - effectively, a censorship cartel - with no political or judicial recourse, since the government was not involved in it, and the ISPs were in their right, legally speaking.
And they did - to the point where a bunch of websites with forums were blocked outright because of their hands-off policy wrt comments (usually in some particular subforum; it's a fairly common way to keep it civil elsewhere) meant that there were a bunch of posts with links to the document.
The end result is that a bunch of completely unrelated stuff was blocked in Australia outright for a while, by private companies in charge of communications acting in unison - effectively, a censorship cartel - with no political or judicial recourse, since the government was not involved in it, and the ISPs were in their right, legally speaking.