This Article suggests that there is Proper Methodology that courts apply when reviewing cases at the intersection of due process and equal protection. Briefly, courts operate under a rule that heightened review applies if either a fundamental right or a suspect class is involved in a case, and that rational basis review applies if neither is involved (the "Rule"). Two primary exceptions to the Rule exist, and this Article identifies them as the "Logical" and "Ill Motives" Exceptions. The Logical Exception applies when a court need not apply heightened review because a law fails rational basis review. The Ill Motives Exception applies when a law fails rational basis review because the sole purpose behind a law is an ill motive. The Rule and the Exceptions provide the Proper Methodology to be applied in intersection cases. The genesis for the Article arose in the context of analyzing the constitutionality of laws that ban marriage between persons of the same sex, popularly called "gay marriage." Notwithstanding the fact that the right to marry is a fundamental right, confusion exists as to whether gay marriage bans are subject to rational basis review or heightened scrutiny. Some of the confusion exists because the Supreme Court has not decided where sexual orientation fits in the equal protection paradigm. But this void is responsible for only part of the confusion. This Article exposes another dangerous source of confusion-a tendency to allow popular discourse to shape the legal analysis in sexual orientation discrimination cases, resulting in what this Article calls the "Collapsible Error." Courts commit the Collapsible Error when they conflate the equal protection question ("Are gays a suspect class?") into the due process question ("Is there an underlying fundamental right?") by defining the underlying right by the group targeted by the law-gay marriage-and then limiting the analysis to substantive due process ("Is there a fundamental right to gay marriage?"). This Article explores why committing the Collapsible Error is a denial of the due process and equal protection rights of gays because it results in an unjustifiable deviation from the Proper Methodology that is applied in cases involving other types of discrimination. Understanding and applying the Proper Methodology is not only a matter of judicial integrity, but it also is an opportunity to bring gays into the Constitution's fold.