Laws and morality should not be seperated because it is, in all honesty, not possible. Any just law is based upon morality, and is created for the embetterment of human kind. Many of them should be common sense because every person has a conscience.
When you attempt to seperate laws and the morality behind them you end up with stupid, idiotic, and useless laws such as "It's illegal to tie a giraffe to a lamp post in Atlanta, GA." It is not possible, and I don't see how you think that it could be.