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While juggling a collapsing economy and major initiatives during his first months in office, President Obama tackled - and cooled - a contentious issue that has simmered for almost 10 years: embryonic stem cell research. His March 9 executive order fulfilled a campaign promise to lift his predecessor's restrictions on its federal funding.

The president outlined his new approach, leaving the details up to the National Institutes of Health. A week ago, the NIH unveiled its draft guidelines.

The new regulations would permit federal support for research with stem cell lines derived from embryos that are created, but not used, for fertility treatments. There are hundreds of thousands of such excess embryos in storage, most scheduled for eventual destruction regardless of scientists' activities. At the same time, federal support would not be permitted for work with stem cell lines derived from embryos created with cloning techniques - if any are ever successfully produced.

This is a thoughtful approach, and the right thing to do.

There are very good reasons - technical, ethical and political - why cloning-based stem cell research...