This is actually a rather important principle, and most people don't realize how many federal laws that work at the state level use funding carrots rather than criminal-punishment sticks for enforcement. For instance, the penalty for not following the unpopular and eventually dismantled "No Child Left Behind Act" was that your state would not receive federal education funding.
> The Act required states to develop assessments in basic skills. To receive federal school funding, states had to give these assessments to all students at select grade levels.
