The translucent dot of cells floating in the petri dish of a cloning lab has not yet taken the shape of a person, but someday it could. Does it deserve protection?

That’s the ethical question now being debated in Washington, D.C., where lawmakers are in the midst of a new struggle to regulate cloning.

This abstract debate suddenly turned real last fall with the startling news that the Massachusetts biotech company Advanced Cell Technology had created the world’s first cloned human pre-embryos. Although all the embryos died within six days, it was a wake-up call to the promise, and peril, of the new technology.