1) TSA has never caught a terrorist with an ID check. Of course, they've never caught a terrorist by any other means, either, so maybe that's a bad example.

2) The Times Square bomber got on a plane, even with ID.

3) No ID of which I am aware has a line of text, symbol, or check box denoting "Do Not Fly List" or "Registered International Terrorist". Since the TDC does not check the name on the ID against lists of Bad People, there is no way that such an ID check will ever lead to the discovery of a Bad Person. Of course, not all Bad People are in the International Registry of Bad People Who Shouldn't Ever Fly But Are Not Wanted by the Police, so even if the TDC DID compare the ID to such a magic list, it still wouldn't catch Bad People who weren't on the List.

4) Given the frequency of underage drinkers and illegal aliens gaining access to fraudulent IDs, even a person who was #1 on the IRoBPWSEFBANWbtP could easily obtain a fake license from some college kids in Ohio or some back alley guys in Nogales, and get past the TDC without breaking a sweat. The TDC would probably like such a Bad Person, because the ludicrous nature of the ID check would put a big grin on the Bad Person's face, which the TDC would interpret as a friendly gesture. "What a nice man!" the TSO would think of the horrific international terrorist he had just allowed to pass into the sterile area.

6) The original intent of the TDC was merely to limit the number of people entering the airside areas to ticketed passengers only, not to make anything more secure, but to limit the number of people who had to be screened, because the lines at the c/p's were backing up after 9/11 and becoming untenable. Much like George Carlin's "Stuff" routine, however, the reduction of the line then allowed TSA to add more time-consuming procedures to the c/p, which then lengthened the lines even more than they had been prior to 9/11. When you get too much stuff, you get a bigger house. But then you have empty space, so you get more stuff to fill it, and then you have too much stuff and need a bigger house again...

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Do you have any data with supports the opposite opinion? The US government is infringing upon peoples' freedom of movement without due process. The onus is on them, and their supporters, to provide evidence that this infringement of civil liberties has a positive benefit - not a POTENTIAL or THEORETICAL benefit, but an actual, measurable benefit - in order to make such an infringement reasonable, and therefore Constitutional.

Such evidence of any such benefit has never been put forth. The best anyone has ever been able to manage in a public forum has been a statement (I think it was by Kip Hawley while he was head of TSA) that, "ID matters!" Said with such conviction and solemnity, it seems, that everyone in the US has swallowed that line of tripe with a smile and asked for more.