I'm puzzled about how the military's "Don't Ask, Don't Tell" policy -- or for that matter, any exclusion policy -- can be justified as to lesbians. As I understand it, the main argument in favor of such a policy for male homosexuals is that in all-male or nearly-all-male combat units the possibility of sexual tension may undermine unit effectiveness. I'm skeptical about this argument, but it at least seems plausible.
Yet it doesn't seem to apply to lesbians, since presumably they would very rarely be serving in all-female units, and never in all-female combat units. Moreover, even if we set aside antidiscrimination arguments and focus solely on military effectiveness (which may or may not be the right approach, but let's use it here), it seems lesbians would tend to make better soldiers than straight women:
They are less likely to get pregnant.
They seem less likely to get sexually transmitted diseases.
If the stereotypes about lesbians tending to act in more masculine ways are generally accurate -- hard to tell, for obvious measurement reasons, but that seems to be the conventional wisdom -- then that cuts further in favor of lesbians as opposed to straight women. Many women may well make great soldiers, but if we're speaking about generalities, and the military policy is generally defended using generalizations, I'm happy to at least tentatively assume (as I suspect would the military) that stereotypically masculine traits and attitudes tend to be more useful for soldiering than stereotypically feminine ones.
Is it just that the military fears that straight soldiers will so dislike lesbians that this itself would cause morale problems? I guess that just doesn't strike me as that factually plausible. Is it that the military wants to treat male and female homosexuals equally, for fairness or public relations reasons? That seems odd: Can it really be that discriminating against homosexuals is just fine, discriminating against women (as the military long has done, and still in considerable measure does) is just fine, but discriminating based on sex among homosexuals is wrong, even when there's a perfectly sensible argument for such discrimination? Or is there something else I'm missing here?