Nothing like "strict scrutiny" or "rational basis review" stuck out.
Here are a couple takes on that question.
Jack Balkin:
Windsor is a reminder of the fact that the scrutiny rules we teach our students as gospel are a relatively recent invention--less than fifty years old. They were designed to make it easier to think about when laws are constitutionally unequal. But sometimes they don't really assist our understanding of the issues; they just get in the way. In fact, you actually can explain Windsor in terms of the existing structure-- it's a "rational basis with a bite" case, and that's how the casebooks (including the one I co-author) will probably classify it. But we should be able to look behind the doctrinal superstructure, which explains little, and see the deeper principles at stake, principles that have a long history in American constitutional thought. DOMA singled out gay people for special burdens in an important area of social life; it declared their marriages less valuable, and therefore, to that extent, it made them second-class citizens. Even if this wasn't obvious in 1996, it is increasingly obvious today.
Ilya Solim:
As with some of Kennedy’s other important opinions, the exact meaning of this one is hard to figure out. But what he seems to be saying is that the the Congress’ pursuit of purposes beyond the normal scope of federal authority in DOMA makes the law a “discrimination... of an unusual character” and justifies imposing tougher scrutiny under the Fifth Amendment. According to longstanding precedent, the Fifth Amendment imposes on the federal government equal protection antidiscrimination principles that the Fourteenth Amendment imposed on the states. Fifth and Fourteenth Amendment precedent impose different levels of scrutiny on different types of laws, depending in part on the purposes those laws pursue. Here, Kennedy suggests that the level of scrutiny is higher if discriminatory federal laws are intruding into areas generally left to the states. Later in the opinion, he notes that ““‘[d]iscriminations of an unusual character” [require] especially require careful consideration” to determine whether they are based on “animus” against a particular class, and that “DOMA’s unusual deviation from the usual tradition of recognizing and accepting state definitions of marriage... is strong evidence of a law having the purpose and effect of disapproval of that class [gays and lesbians].”
