William Dembski, the "Isaac Newton of information theory" *snort*, on the other hand decided to try his hand at the Common Designer gambit. He quote-mines some hay from an evolution for dummies book, builds a strawman and promptly lights it on fire. The argument basically goes that animals that seem similar only appear that way because they were made by the same "Designer" (wink, wink). Forget for the moment that this doesn't explain things like endogenous retroviruses, homologies, and the twin-nested hierarchy that all living things fall into. This argument should be considered sacrilege by almost every theist. This arguments puts the "Designer" into a very small box. If this "Designer" is of the omnipotent variety then it should be trivial for "It" to similar creations with very different genetic codes. Plus the fact that the codes for similar creatures fall into a specific hierarchy where it appears that the creatures evolved without any supernatural assistance make this "Designer" into a trickster that wants humans to chase their own tails when it comes to the natural world. As a Discordian, I have no issue with this but I doubt it's the message the Discovery Institute wants to send out.
Thankfully Thunderf00t has put up a better explanation to why the "Common Designer/Common Design" argument fails mightily.
So in summary, the Discovery Institute feels like it's not their job to put forth any actual evidence for the intelligent design hypothesis. They seem to think that if that they muddy the waters about naturalistic evolution enough that they will somehow win by default. To that I will quote philosopher Francisco Ayala at the McLean v. Arkansas trial almost 30 years ago:
“My dear young man, negative criticisms of evolutionary theory, even if they carried some weight, are utterly irrelevant to the question of the validity or legitimacy of creation science. Surely you realize that not being Mr. Williams in no way entails being Mr. Ayala!"