There’s a hidden architecture beneath equal protection law, and it comes down to one deceptively simple question: Which kinds of discrimination get treated as serious enough to trigger real constitutional scrutiny?
The answer is: not many.
That’s because the Equal Protection Clause doesn’t treat all classifications equally. Some (like race) get the Court’s strictest eye. Others (like sex) get a middle level of protection. And everything else? It usually gets the benefit of the doubt.
This is what we mean when we talk about suspect classifications.
A Three-Tier System
Equal protection analysis operates on a tiered framework:
Strict scrutiny: Applied to laws that classify based on race, national origin, or alienage (in some contexts). The government must prove the classification is narrowly tailored to serve a compelling interest. Almost nothing survives this test.
Intermediate scrutiny: Used for sex and illegitimacy. The government must show the law is substantially related to an important government interest. This test has more teeth, but still allows some flexibility.
Rational basis review: Everything else. The law only needs to be rationally related to a legitimate government purpose. It’s an extremely deferential standard, and the government almost always wins.
So, when a group asks the Court to recognize it as a suspect or quasi-suspect class, it’s really asking for meaningful protection. To move from the realm of deference to the realm of scrutiny.
The Criteria
The criteria we now associate with suspect and quasi-suspect classifications grew out of Carolene Products, Footnote 4—“discrete and insular minorities.”
That phrase became a touchstone in later equal protection cases, particularly during the Warren and Burger Courts. Over time, the Court began to articulate a multi-factor test, not in a single opinion, but across many cases.
These factors include:
History of purposeful discrimination (e.g., race in Brown v. Board of Education).
Immutable or obvious characteristics (e.g., sex in Frontiero v. Richardson).
Political powerlessness—a group unable to protect itself through the ordinary political process.
Relevance of the trait to societal contribution—whether the classification bears any connection to ability or merit.
These aren’t hard-and-fast rules, but they’ve guided the Court’s decisions about why race, sex, and national origin deserve extra constitutional attention.
Why the Court Blinked on Sexual Orientation
By these criteria, sexual orientation seems like a strong candidate for heightened scrutiny. LGBTQ individuals have faced centuries of discrimination. Sexual orientation is not easily changed. And the trait has no bearing on a person’s capacity to participate in society.
But here’s the thing: the Supreme Court has never formally said so.
In Romer v. Evans, Lawrence v. Texas, Windsor, and even Obergefell, the Court struck down anti-LGBTQ laws without assigning a tier of scrutiny at all. Instead, the justices focused on animus, liberty, and above all, dignity.
Why?
Because declaring sexual orientation a suspect class would have had enormous ripple effects. It would’ve meant that all laws drawing distinctions based on sexual orientation would face heightened review—not just in marriage, but in adoption, public accommodations, housing, education, and beyond.
That was a bridge the Court wasn’t ready to cross. So it sidestepped.
You might think of this as judicial caution or judicial compromise. Either way, it left LGBTQ rights formally unanchored in traditional equal protection doctrine, even as the Court extended major substantive victories.
Where Things Stand
Today, at the federal level, sexual orientation is not officially a suspect classification. Lower courts have begun to apply heightened scrutiny in some circuits, but there's no binding nationwide rule. That means future rulings could turn not on principle, but on personnel.
In a constitutional landscape increasingly shaped by cultural conflict, the lack of a clear doctrinal foundation leaves LGBTQ protections more vulnerable than they appear.
And that’s the quiet cost of the Court’s silence.
Should the Court formally recognize sexual orientation as a suspect classification—or does the flexibility of dignity-based rulings serve equality better in the long run?
As much as I agree with Justice Kennedy in Windsor and Obergefell, I feel as though his failure to anchor the right of same-sex couples to marry more securely in a single constitutional provision is what set the groundwork for cases like Masterpiece Cakeshop and 303 Creative. He correctly identifies that marriage is a fundamental right extending to same-sex couples, yet does not seem to apply the strict scrutiny standard that would normally be used to analyze legislation affecting a fundamental right. Instead, in Windsor he states that laws that make "discriminations of unusual character require careful consideration." Obergefell contained equally non-committal language without any express invocation of strict scrutiny.
Less than a decade after Obergefell, the Supreme Court in Masterpiece Cakeshop stated that private business owners could refuse to serve same-sex couples on religious freedom grounds. And in 303 Creative, this was extended even to online services like website building. These cases are grounded in the idea that laws or regulations requiring businesses to serve same-sex couples when doing so would violate the business owner's religious views intrude on the free exercise of religion. Because religious groups are protected classes, these laws or regulations are reviewed under strict scrutiny. But because the rights of same-sex couples were never elevated to the same level of protection as the rights of religious groups, the interests of the former will always fall to the latter.
I think if Justice Kennedy had more clearly given same-sex couples heightened protections and invoked strict scrutiny, it would have avoided the problems that arose in Masterpiece Cakeshop and 303 Creative and would have more accurately effectuated what his intent seemed to be in Windsor and Obergefell.
Are these cleanly-cut tiers impacted at all by Kimberly Crenshaw's concept of intersectionality?