First, there was plain and simple creationism, a Christian idea that, in an ideal Christian world, would be taught as part of any science dealing with the past, including biology (evolution), geology, and presumably history.
But the constitution stood in the way of implementing basic Christian teachings in public schools in the United States, though that battle took decades. Just as creationists were being driven off he landscape, a sort of Battle of the Bulge occurred, in the form of Intelligent Design.
Intelligent Design is a scientific-looking theory which is really just more creationism, and while, as with the actual Battle of the Bulge, creationism expanded briefly, it was again beaten back by legal recourse to the Constitution.
There is now another battle being fought, which is sort of a re-worked version of the “teach the controversy” gambit, which makes use (or, really abuse) of the concept of “academic freedom” to force, once again, Christian ideology down the throats of our unsuspecting youth, in public school.
Joshua Rosenau has been there for much of the latter part of this history, in his role with the National Center for Science Education and as a blogger, consultant, speaker, and writer. And, most recently, he has written a law review article on the role of Dover, and the situation pre, with, and post the Dover decision, in which Intelligent Design was deemed by a federal court to be yet another form of creationism.
Josh wrote up a brief description of his law review article here, and on that blog post you can access a PDF file of the whole thing, which is close to 70 pages long.
Excellent bedtime reading for anyone interested in the topic!
Rosenau, Joshua (2010). Leap of Faith: Intelligent Design’s Trajectory after Dover UNIV. OF ST. THOMAS JOURNAL OF LAW & PUBLIC POLICY, IV