Almost five years ago, I wrote a post arguing that the English language needs a new word. From July 17, 2004:

The English language needs a word for when advocates on both sides of an ongoing debate switch rhetorical positions, and yet they insist on decrying the inconsistency of their opponents while overlooking their own inconsistency. You can see it in politics whenever there is a change in power. Advocates from the party that loses power switch to the standard what-you-say-when-you're-the-opposition arguments, and those from the party that is now in power switch to the standard what-you-say-when-you're-in-power arguments. You never have to wait very long before one side tries to outfox the other by trotting out what their opponents said back before the power switch: "Aha!" an advocate for one side will say, "But back in 199_, you took the opposite position!" Well, of course: back then, everyone took the opposite position. I don't know of a word for this particular phenomemon, but I think we need one.

Too bad we never did come up with a word for this, as I could have used it to describe this new essay by Dahlia Lithwick.