When exponential general-purpose molecular manufacturing becomes a practical reality, it will immediately create several severe risks—and each risk will tempt a simple and extreme solution. However, a patchwork of extreme solutions will be both destructive and ineffective. For example, some have proposed halting nanotechnology research entirely. Attempting this would not achieve the desired goal; instead, it would relocate the research to less responsible venues. The risks might be delayed by a few years, but would be far worse when they appeared because the technology would be even less controllable. To take another example, economic upheaval might be prevented by strict commercial licensing of all uses of the technology. This has two problems. First, digital protection schemes for commercial products have often proved quite easy to crack. Second, if the technology is so restricted that it cannot disrupt existing economic systems, continuing poverty will kill millions of people each year, fueling backlash, social unrest, espionage, and independent development. Each risk must be reduced by some means that does not exacerbate others. This will not be easy, and will require creative and sensitive solutions.
That's a basic overview of the complex challenge we are facing. Read a more detailed analysis here.