The new AEI Federalist Outlook:

State attorneys general, for example, paint their investigations and litigation campaigns as "federalism in action," and they strongly protest when federal agencies assert regulatory prerogatives. Ironically, such claims often receive a respectful hearing from conservative justices who, constitutionally, have supported states' powers against federal overreach. Yet when those "pro-state" justices do support broad claims of federal preemption, their critics charge them with simply voting their pro-business, antiregulatory ideology over their purported federalism principles.

This last charge rests on shaky empirical foundations, for the conservative justices do not reflexively vote for preemption. If anything, liberal justices are more likely to vote reflexively against preemption. It is important to understand which decisions are right and why, because contrary to myth, preemption and federalism are not polar opposites.