State officials have spent the last 15 years attempting to devise a regime so they can force out-of-state vendors to collect sales taxes, but the Supreme Court has ruled that such a cartel is not permissible without congressional approval. Congress is currently considering the Main Street Fairness Act, a bill that would authorize a multi-state tax compact and force many Internet retailers to collect sales taxes for the first time. Is this sensible? Are there alternative ways to address tax “fairness” concerns in this context?