WASHINGTON – It is a good idea to expand federal funding of embryonic stem cell research. It is a bad idea to do that without prohibiting research that uses embryos created specifically to be used in research and destroyed.

What is deeply troubling about the Castle-DeGette stem cell bill that passed the House and will soon roar through the Senate is that it combines the good with the bad: expansion with no limit.

The expansion – federal funding for stem cells derived from some of the thousands of discarded fertility-clinic embryos that are already slated for extinction – is good because the president’s sincere and principled Aug. 9, 2001, attempt to draw a narrower line has failed. It failed politically because his restriction – funding only research on stem cells from embryos destroyed before the day of that speech – seems increasingly arbitrary as we move away from that date.

It failed practically because that cohort of embryos is a diminishing source of cells. Stem cells turn out to be a lot less immortal than we thought. The idea was that once you create a line, it could replicate indefinitely. Therefore, you would only need a few lines.

It turns out, however, that as stem cells replicate, they begin to make genetic errors and to degenerate. After several generations, some lines become unusable.

In addition, there has been a new advance since 2001. Whereas stem cells in those days had to be grown on mouse feeder cells, today we can grow stem cells on human feeder cells. That makes them far more (potentially) therapeutically usable.

For both of these reasons, the August 2001 policy is obsolete. Accordingly, Congress will soon federally fund research from embryos newly created in IVF clinics.

It simply will not do for opponents of this expanded research to say that the federal government should not force those Americans who find this research abhorrent to support it with their taxes. By that logic, we should never go to war, or impose the death penalty, except by unanimous consent of the entire population. We make many life or death decisions as a society as a whole, without being hostage to the sensibilities of a minority, however substantial and sincere.

Nonetheless, Congress’ current vehicle for expanding this research, the Castle-DeGette bill, is extremely dangerous. It expands the reach for a morally problematical area of research – without drawing any serious moral lines.

The moral problem for that majority of Americans who, like me, don’t believe that a zygote or blastocyst has all the attributes and therefore merits all the rights of personhood, is this: Does that mean that everything is permissible with a human embryo?

Don’t they understand the real threat? It is not so much the destruction of existing human embryos – God knows, more than a million are already destroyed every year in abortions, thousands doomed to die in IVF clinics. A handful drawn from fertility clinics where they will be destroyed anyway alters no great moral balance.

The real threat to our humanity is the creation of new human life willfully for the sole purpose of making it the means to someone else’s end – dissecting it for its parts the way we would dissect something with no more moral standing than a mollusk or paramecium. The real Brave New World looming before us is the rise of the industry of human manufacture, where human embryos are created not to produce children – the purpose of IVF clinics – but for spare body parts.

It is this creation-for-the-purpose-of-destruction that needs to be stopped – and it does not matter whether that creation occurs by joining sperm and egg (as the Jones Institute in Virginia has already done) or by cloning a cell from an adult, turning it into a human embryo, and then destroying it for its stem cells.

Both in my writings and as a member of the President’s Council on Bioethics, I have advocated this dual policy for years: expand federal funding of stem cell research by using discarded embryos but couple that with a firm national ban on creating human embryos for any purpose other than the birth of a human baby. We finally have a chance to enact this grand compromise – but only if a majority of senators insist that the welcome expansion provided in the Castle-DeGette bill, which will yield a near endless supply of embryonic stem cells, cannot take place unless the door is firmly closed now, while we still have the chance, on the manufacture of human embryos for research and destruction.

Charles Krauthammer is a Washington Post columnist. Contact him by writing to letters@charleskrauthammer.com.