Actually, the supreme court decision that struck down the previous abortion law laid out a course for parliament to bring in a new law and all but suggested a law based on different rights at different stages of gestation.  The politicians just did not follow up and get the job done.  So I am not sure I would agree that the jurisprudence is as clear as you suggest.  

I would also point out that we are the only major nation not to have any law on the books governing abortion in any way.  In a narrow legalistic sense, a woman has the right to abort a fetus the day before delivery.  Perhaps we are the most enlightened nation in the world and have figure out a better way that has eluded all the other progressive nations of the world, or perhaps we just have a bunch of chicken-sh*t politicians who don't have the cajones to do their jobs and take on a difficult issue.  I am guessing it is the latter.