Issue I care about: abortion.

Questions:
1.) Is there any idea scientifically about whether life begins at birth vs. at conception?
2.) What constitutional basis is there for people to outlaw abortion?
3.) What are the current political parties stances on abortion?

Sources:
http://www.feministe.us/blog/archives/2010/08/26/when-does-life-begin/
http://www.npr.org/blogs/13.7/2011/09/14/140397576/when-does-life-begin
http://familydoctormag.com/sexual-health/251-when-does-life-begin-medical-experts-debate-abortion-issue.html
http://www.rnclife.org/brochure/rprolife.html
http://www.euthanasia.com/demo.html

Answers
1.) There is no scientific consensus about when life begins. Some will say it's when heartbeats can be registered, others when brain activity can be detected, and others still at conception and birth. There are too many different "definitions" for there to be consensus, even among scientists.
2.) There is no constitutional basis for the outlaw of abortion. Pro-life activists will incite that abortion is murder, but because there isn't a consensus as to when life begins, there can't be any proof that abortion is murder.
3.) The Republican party generally states that they are the pro-life party, whereas the Democratic party states that they are the pro-choice party. However, there is some line blurring. Some Republicans identify themselves as pro-choice, and some democrats identify themselves as pro-life.