How do you defend Jared Loughner

It is not a "who done it", it is a "why did he do it".
The real action in this case is keeping him alive - I expect both a state and a federal death penalty prosecution.

Why would you want to keep this type of person alive?

Giving the state the power to kill is giving up entirely too much. The state is a legal fiction. You can live a long live in the United States and never meet the State of California. You'll never meet the United States government. You'll meet individuals who act on behalf of these necessary facts of fiction, telling you that they are acting on behalf of your welfare. That's all fine and dandy, I just don't want fiction killing people.