Just to add a bit to what schraf wrote.
I'm not fully sure of what you mean, though. What is it before it becomes human? A living ball of cells? A humanoid embryo?
The question really boils down to what defines "human". Ethical/moral dimension aside, I think a case could be made that it is the advanced brains that come closest to distinguishing our species from most others, specifically the prefrontal association complex of the cerebral cortex - the main control processor that appears to involve planning and abstract thought. There is, however, a difference between when "life" begins - which is probably the moment of conception - and when "human life" begins - somewhere during the late second trimester with the development of the pre-frontal cortex. It's not a great dividing line, primarily because there's no hard and fast moment when the association becomes "functional", but the idea is at least biologically tenable.
Do the laws take this into account?
No. The Supreme Court (US) defines life as beginning when the neonate takes its first breath. I think this is neither biologically nor ethically defensible. Especially since the limit of viability has been continually pushed back by technology to now hovering somewhere around the 21st week of gestation (I could be wrong on that - and in any event a premie that early has some severe developmental problems).
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