This was a far cry from the old Lindsley standard. States could no longer defend statutory distinctions between men and women by offering merely a "reasonable" explanation; and the burden no longer lay with the petitioner to prove that the distinctions were arbitrarily drawn. Now the state had to prove that gender classification served an important governmental objective, and they must show that this classification was essential, or substantially related to the achievement of that objective.
The second part of this test proved particularly difficult for states to pass. They might convince the court that their law pursued an important and appropriate objective—but proving that it was necessary to treat men and women differently to achieve that objective was far more difficult. Thus when Alabama passed a law freeing all women from the obligation to pay alimony because the state did not want to impose financial burdens on poor women, the Supreme Court said this was unconstitutional ((Orr v. Orr). While the governmental objective was legitimate—providing financial relief to the poor—it was not reasonable or fair to assume that salary differentials between spouses always corresponded with gender. In fact, the Court said, the law unfairly punished poor men and advantaged wealthy women.
But the new test or intermediate standard established in Craig v. Boren was not impossible to pass. In 1981, in Michael M. v. Superior Court of Sonoma County, the Supreme Court upheld a California statutory rape law that forbade men, but not women, over 18 from having sex with non-spousal partners under 18. The petitioner argued that this treated men unfairly. But the Court held that the governmental objective was important—preventing teen pregnancy—and the different treatments accorded men and women were "substantially related" to the achievement of that objective. Since men could not get pregnant (even men under 18) the law need not protect young men in the same way that it could protect young women.
Also in 1981, the Court held that federal laws excluding women from the military draft were not unconstitutional as the use of a gender classification was "substantially related" to the achievement of an "important governmental objective." Since the primary purpose of the draft was to identify a pool of combat-capable persons, and since women were excluded by the military from combat, the unequal treatment of men and women was defensible.
Classifications based on gender are still not subjected to the same level of scrutiny as classifications based on race. State laws that treat men and women differently are still more easily defended than laws that differentiate on the basis of race or citizenship. But since Boren, the Court has raised the legal bar for the states attempting to incorporate gender classifications into their laws; it has introduced, in effect, an intermediate standard, somewhere in between the Lindsley test and "strict scrutiny," when judging gender classifications.
The bottom line: Don't let anyone ever tell you that an eighteen-year-old boy's interest in drinking beer is not important.