You can't make a medical condition a crime. People who willing choose to break the law had a choice.
Sure you can - look at the the 10 of thousands of ridiculous laws that are currently on the books...
Obviously, you missed the irony in my comment - making it illegal to be mentally unstable versus another gun law being equally as effective - THAT'S THE POINT - more gun laws would work just as well.
My Lord - quit taking everything literally....