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Though Chief Justice Roberts ultimately provided the fifth vote upholding the Affordable Care Act (ACA) under the Tax Power, his was also one of five votes finding the ACA exceeded Congress’ power under the Commerce Clause.

The doctrinal basis for Roberts’ Commerce Clause analysis was hotly contested. While Roberts argued that the ACA’s purported exercise of Commerce power “finds no support in our precedent,” Justice Ginsburg accused the Chief Justice of failing to “evaluat[e] the constitutionality of the minimum coverage provision in the manner established by our precedents.”

These diametrically opposed perspectives on “precedent” might prompt observers to ask whether Roberts and Ginsburg considered the same cases as controlling. This Visual Guide shows that though the justices agreed on relevant cases, they disagreed on which opinions within those cases properly stated the law. Both Roberts and Ginsburg implicitly adopted the reasoning of prior dissents and concurrences as well as majority opinions. The map illustrates how competing lines of Commerce Clause opinions constitute a long-running doctrinal dialectic that culminated – for now – in NFIB v. Sebelius.

This Visual Guide is a single-page PDF "poster" designed to serve as quick reference to the doctrinal debate.