They can't. Congress is responsible for regulating interstate commerce and creating intellectual property laws. Even a blanket statement that US laws don't apply to the Internet would have a detrimental effect. In the long run, the only way for Congress to not harm the usefulness and freedom of the Internet is for legislators to understand the Internet and specifically craft laws to avoid negative side effects.

> Congress is responsible for regulating interstate commerce and creating intellectual property laws.

They're not obligated to do either of those things - they merely have the authority to do so.

> In the long run, the only way for Congress to not harm the usefulness and freedom of the Internet is for legislators to understand the Internet and specifically craft laws to avoid negative side effects.

Was that true for electricity? How about railroads or telephones?

Heck - I'd argue that the only thing that Congress has ever "understood" is alcohol, and they've botched that at least twice.