Well, if you are talking about the US: Federal law trumps state laws.
However, there are limits on federal law: It can only cover specific areas, such as interstate commerce (what that exactly means is a topic of frequent debate, but is used to justify federal anti-drug laws and environmental regulations).
Congress CAN, however, "encourage" states by way of economic incentives (e.g. transportation fund) to behave in certain ways.
Now that we've thrown 'em off the trail, use the form below to get in touch with the people at Engadget. Please fill in all of the required fields because they're required.
Well, if you are talking about the US:
Federal law trumps state laws.
However, there are limits on federal law: It can only cover specific areas, such as interstate commerce (what that exactly means is a topic of frequent debate, but is used to justify federal anti-drug laws and environmental regulations).
Congress CAN, however, "encourage" states by way of economic incentives (e.g. transportation fund) to behave in certain ways.