How do you define an organism?

Despite being defined in high school biology textbooks everywhere, this is a question the National Research Council (NRC) is currently asking. They are particularly interested in the context of their Select Agent list, which designates dangerous organisms with the potential to be used as weapons. This was generally clear-cut before; Bacillus anthracis (the cause of anthrax) was Bacillus anthracis, it was dangerous and controlled, and Bacillus subtlis (causes no disease) was different and benign. But these days, where synthesizing DNA is becoming cheaper and widespread, that distinction may not hold. What if someone were to take a non-controlled organism, and give it some toxin genes from a controlled organism? If this organism looks like the benign one, but causes disease like the controlled one, which is it? Should we be defining an organism based on its DNA sequence? Read the full story here.