How about defamation of character. Someone gets online and tells lies about you to such a point that it ruins your life. What is supposed to happen. Nothing?

It's not a crime. You are not going to jail.

Says who? Maybe the federation has a law that states that intentionally spreading falsehoods with the intent of damaging someone's reputation is a crime punishable by revoking privileges or requiring their public statements to be reviewed by some regulatory body. Maybe they go even further and do jail people for this, in a society where reputation is as important as it is in the federation damaging someone else's intentionally using information you know to be false to damage it may be taken far more seriously.

But you have been injured. I remember a case about a woman who went online and told lies about another woman. The injured party got a lawyer and sued.

Keep in mind what the damage in these cases are. In the federation losing money isn't a concept. To compensate for the lose of reputation all you can really do is retract the statement. I can't give you a non existent currency.