Selling a soul for progress

It looks like US government funding for stem cell research has been hijacked again following a decision and temporary injunction by a district court that work involving embryonic stem cells violates a law passed in 1995 regarding the destruction of human embryos. The wording of this bill is strange it essentially bans research in which "a human embryo or embryos are destroyed, discarded, or knowingly subjected to risk of injury or death greater than that allowed for research on fetuses in utero". There are two wrinkles here, firstly stem cells are mostly taken from embryos from early term abortions and would be discarded anyway and secondly where that isn't the case cells can be taken from a blastocyst, this is a clump of cells about 3 days old and contains about 150 cells (for comparison the brain of a fly contains about 100,000 cells). The point is that there is no "embryo", it's just a clump of cells.

I find it strange that the mainly religious "pro-life" lobby in the USA can take an ethical position with no apparent justification other than some woolly unsubstantiated notion that particular cells are endowed with special properties, namely a "soul", when all other cells (containing exactly the same molecules) are not. I am all for debate and rationalisation when deciding what is ethical but it has to be even handed, you can't expect one side of the argument to be held accountable to and responsible for producing scientific evidence that a clump of cells cannot suffer whereas the other side just states an opinion based on bronze age mythology and apparently that's enough?

Where is the scientific evidence for souls?