This Article explores the question of how the courts should calculate the denominator in the just compensation equation. The denominator is the amount of property a claimant owns, against which the effects of regulation will be measured. If a landowner owns a single acre that is severely regulated, the takings fraction for the amount of property taken compared to that owned will approach one. If, on the other hand, the landowner owns 100 acres and only one is regulated, the amount of harm is only 1% in comparison to the total amount owned. This Article advocates a paradigm shift in the Supreme Court's Takings jurisprudence on the denominator question. While many commentators have struggled with the issue of whether the government taking $1.00 from a homeless person should be treated differently than taking $1.00 from a millionaire, none has satisfactorily explained how the context of the taking and the landowner's total holdings are relevant to the takings analysis. Richard Epstein says they are irrelevant; the taking is the same regardless of the homeless person or the millionaire's total or past holdings. The Court has said there is a difference but has not given any kind of satisfactory justification. This Article attempts to justify the distinction with insights from traditional property law.

In particular, the Article argues the Court should treat large landowners differently than small landowners in making the denominator determination, even though the large landowner may no longer own any neighboring land. In basing the argument on a little-known nineteenth-century lateral support case, in which a landowner was not entitled to damages for harm because his own actions made himself vulnerable to the damage, the Article explores the question of the landowner whose severance of property makes her more vulnerable to the harm caused by a new regulation.