Jack Balkin has an illuminating post on the Solomon Amendment decision, Rumsfeld v. FAIR.
Balkin explains why he was a "reluctant" supporter of the litigation against the Solomon Amendment:
...I believed that, if successful, these lawsuits might cause problems for other areas of antidiscrimination law, in particular, in the area of Title VI and Title IX law. The reason is that Title VI and Title IX impose antidiscrimination obligations on schools that receive federal funds. If the FAIR and Yale plaintiffs had first amendment rights to be excused from the Solomon Amendment, racist and sexist institutions might claim that they were entitled to be excused from Title VI and Title IX obligations. There are ways to distinguish the two situations, but it requires some fairly fancy footwork and it might cause even more problems down the road. Therefore, when I joined the Yale suit as a platinff, my preference was for a much narrower theory of the case, one that would pose no danger of undermining federal antidiscrimination laws.
I think this helps explain why FAIR lost, and lost so badly, in the Supreme Court. There was simply no constituency on the Court, and precious little constituency off the Court, for the sorts of broad speech and associational rights being pressed by the litigants in the context in which they pressed it. Aside from the interesting doctrinal issues raised, neither conservatives nor liberals liked the claims. Conservatives defer to the perceived needs of the military and to Congress's "judgment" about those needs, even though that judgment was largely a fiction in this case. (There was no evidence that the military needed access to law school buildings in order to recruit a sufficient number or quality of law students to provide legal services. Even the Defense Department initially opposed the Solomon Amendment as unnecessary and counterproductive.)
Liberals were never enthusiastic about the broad associational rights announced in Boy Scouts v. Dale, which was decided by the narrowest margin (5-4), because they worried about its effects on federal and state antidiscrimination laws. Balkin, correctly in my view, reads Chief Justice Roberts' opinion to confine the associational freedom protected in Dale largely to membership issues. But whereas Balkin celebrates that limitation of associational freedom, I think it is unduly narrow, both as a matter of the Court's associational freedom precedents and as a matter of principle.
In short, for conservatives, Rumsfeld v. FAIR was a chance to reassert Congress's traditional power over national defense; for liberals, the case was a chance to narrow the reach of Dale and implicitly to reassert government's power to enforce antidiscrimination regulations. If neither conservatives nor liberals support your case, you have no case.
Also worth reading in Balkin's post is this insight regarding the Court's suggestion that law schools are now perfectly free to post notices, etc., announcing that military recruiters are not welcome:
If a school (and its faculty) were repeatedly to send the message that its black students were not welcome, even though the school did nothing else to prevent the students from attending the school, I have little doubt that the school would have violated Title VI of the 1964 Civil Rights Act. Similarly, if a restaurant had signs at its entrance saying "blacks go home" and "we resent serving blacks" and placed those signs deliberately in order to make blacks feel unwelcome, but did not refuse service to those blacks who came inside, the owners of the restaurant would probably be in violation of Title II. In other antidiscrimination laws, equal access isn't simply a requirement of no formal limits on physical access. Equal access usually means that you aren't allowed to send signals that the group is disfavored and unwelcome so as to discourage the group from entering and using the facility.
As a matter of statutory construction, the distinction between the Solomon Amendment and Titles II, VI, and VII may be that the former is solely an "equal access" requirement (e.g. "you must simply let us in, if you let in others") whereas the latter statutes are broader, generalized "equal treatment" commands (e.g., "you must not simply let us in, but treat us with the same dignity and respect as you give others"). But Balkin's argument does suggest that courts may be put in a bind in a future case where a law school pushes the envelope in its efforts to make military recruiters unwelcome. At some point, presumably, a federal court might decide that "unwelcome mats" for the military effectively deny its recruiters equal access.
A related issue Balkin touches on: The Court's opinion suggests that the law schools' freedom to protest on-campus military recruitment (e.g., through "unwelcome" signs and forums) is a matter of legislative grace, not necessarily constitutional law. A future Congress might decide, in response to pesky academics, to adopt a true anti-discrimination requirement for military recruitment, one that mandates not simply equal "access" but substantive equality of treatment. Would the Court hold that these protest rights are protected by the First Amendment? In that event, the Court would have to explain government's power to prohibit other associations from doing the same in, say, Title VII. Or would the Court back off and say that expressive associations, like businesses, may be required not simply to admit those they disdain, but to keep silent about their objections? In that event, the damage done to First Amendment values by this litigation will have been magnified.
UPDATE: Marty Lederman has an interesting reaction to Balkin's post and to the Solomon Amendment decision. Professor Lederman makes the very useful point that (as now construed by the Court) there's a real sense in which the Solomon Amendment requires preferred, not equal, treatment of military recruiters. They, and they alone, are exempt from law schools' general requirement that prospective employers not discriminate against gay law students.
I have to say, however, that I found the statutory argument -- that excluding military recruiters on grounds of violating a generally applicable antidiscrimination policy would comply with the Solomon Amendment -- a bit strained. It seems to me that Congress's requirement of access for military recruiters equal to that given other employers, fairly read in context and in light of its obvious purpose, was really a requirement of "compelled access" for military recruiters if other recruiters were allowed on campus. The statutory issue isn't without doubt, and is more complicated than I'm presenting it here, but on this point I think the Court probably got it right.