Why do we NEED terrorism laws?

Foreign readers can translate this into their own local terms. But the Australian federal government seeks to set up draconian legislation which will allow suspected terrorists to be imprisoned without trial, or judicial oversight. And I am left pondering something that nobody seems to have raised in the public forum - why?

Why do we need to have legislation to deal with terrorism? We have laws against murder, against the use of weapons, against discrimination, and so on. These laws are overseen by judicial control, by habeas corpus, protection from unreasonable seizure and imprisonment. All these things were installed in our tradition because we have seen what happens when judges, police, governments and authorities in general lack oversight. We know about the Star Chamber, about arbitrary prosecution, about police harassment and "verballing" (an Australian practice, probably international, of writing "confessions" that were supposedly made verbally and recorded by police). When did we become amnesiac?

Secret agencies and secret detentions will cause, inevitably, injustices and lead to a loss of rule of law. We know this. So perhaps someone can tell me this - why do we need to revoke these rights and protections? Is there something that terrorists do that is a new kind of crime? They murder - we have laws about murder. They act in conspiracy - we have laws against conspiracy. They use "weapons of mass destruction" (i.e., bombs) - we have laws to control that too.

Either fix those laws in a manner consistent with our legal protections and rights, or use them as they are. We do not need new Star Chambers.