Subjudice is basically a restriction on what the media can do while a criminal proceeding is under way.
Defamation. Most lawyers I know dread the client who comes in wanting to sue someone for defamation. They almost always underestimate the time, resources and money that go into getting a defamation matter in to court and significantly overestimate how much they will get in damages. That’s not to say that you can’t be sued for harming someone’s reputation by what you say on the net, but common sense will usually help you decide what’s appropriate and what isn’t.
All this is just IMO and MOO. If you think you are at some legal risk then go see a lawyer, don’t base your understanding of the law on stuff you see written by anonymous posters on the net. But by the same token don’t be bullied or scared into thinking your feelings and beliefs are not valid or welcome. We are all human being and humans are full of passion. Sometimes that passion makes us do awful things (like kill people) and sometimes it makes us do beautiful things (like put flowers on a bridge).