The Supreme Court decided that Title I of the Americans with Disabilities Act was unconstitutional, insofar as it allowed states to be sued by private citizens for money damages.

Ash was a security guard who had a lifelong history of severe asthma, and Garrett was a nurse who had been diagnosed with breast cancer requiring time-consuming radiation and chemotherapy treatments.

However, the majority opinion also stated that part of the ADA to lack the "congruence and proportionality" required when Congress exercises its enforcement power under the Fourteenth Amendment, citing City of Boerne v. Flores (1997).

In this case, the Court held that Congress, like the judiciary, was required to use rational basis review of state action, with its presumptions favoring constitutionality.

The Supreme Court decided that the legislative record of the ADA "fails to show that Congress did in fact identify a pattern of irrational state discrimination in employment against the disabled."

However, even with this exception, the accommodation duty far exceeds what is constitutionally required in that it makes unlawful a range of alternate responses that would be reasonable but would fall short of imposing an 'undue burden' upon the employer.

Even in cases of racial discrimination in which the courts apply a different standard of scrutiny to government action from rational basis review, evidence of disparate impact is insufficient: "The ADA also forbids 'utilizing standards, criteria, or methods of administration' that disparately impact the disabled, without regard to whether such conduct has a rational basis.

The Supreme Court had held in Village of Arlington Heights v. Metropolitan Housing Corp. (1977) that disparate impact was not proof of discrimination based on "race, color or national origin," which would trigger strict scrutiny.

The problem with the Court's approach is that neither the "burden of proof" that favors States nor any other rule of restraint applicable to judges applies to Congress when it exercises its § 5 power.

(Citations omitted)On "congruence and proportionality," Justice Breyer said that City of Cleburne v. Cleburne Living Center, Inc (1985) and Katzenbach v. Morgan (1966) were precedents that require deference by the Court, not Congress: I recognize nonetheless that this statute imposes a burden upon States in that it removes their Eleventh Amendment protection from suit, thereby subjecting them to potential monetary liability.

Hence "principles of federalism that might otherwise be an obstacle to congressional authority are necessarily overridden by the power to enforce the Civil War Amendments 'by appropriate legislation.'