Are Fatwa Killings Justifiable?

2002-There is wide disagreement inside and outside Nigeria over the fatwa issued by a Nigerian state government against a journalist.
The fatwa, or religious edict, calls for the death of Isioma Daniel of the ThisDay newspaper for saying that the Prophet Muhammad may have approved of the Miss World contest and may have even wished to marry one of the beauty queens.


It is binding on all Muslims wherever they are, to consider the killing of the writer as a religious duty 
Mamuda Aliyu Shinkafi Zamfara deputy governor
It was issued by the deputy governor of Zamfara state in northern Nigeria and calls on Muslims to consider it their religious duty to kill the journalist.
http://news.bbc.co.uk/2/hi/africa/2519595.stm
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How is it a religious duty to kill? I don't get it.  More concisely, since when do religious practices/beliefs supercede pre-existing laws(though I put God first)?
I do not condone what the writer has said, yet I see no reason to call for his head.

I think if the journalist is killed, those who ordered his murder will be arraigned before a court for instigating "contract" killing.  Don't worry, the deputy governor would have to explain himself in court.

Are Fatwa Killings Justifiable?