19th and 20th Groups for domestic anti-terror?

[z3rologic]

Usually I just sit back and read, but on the way back from MEPS this weekend I was talking with my recruiter (who used to be with 1st and 19th Group), and I brought up terrorism on U.S. soil. A while ago I was reading a thread on this forum about how domestic law enforcement isn't exactly up to par on dealing with terrorists entering a high school, or some secondary education facility and taking hostages. Local police, SWAT, HRT, etc, were all talked about; their advantages and disadvantages, and how Posse Comitatus doesn't allow military units like an ODA trained, experienced, and set up to take care of threats like that to be used, though they'd probably be much better at it. My question is if Posse Comitatus would apply to the 19th and 20th Groups being used, as they are a "state owned" entity, being part of the National Guard. The National Guard, when it's operating in its state according to Title 32 of the U.S. Code, is not subject to the prohibition on civilian law enforcement, correct? Federal military forces operate pursuant to Title 10 of the U.S. Code, and National Guard is only considered such when it is federalized. Again, this is all as I understand it... The President could temporarily suspend the law, allowing a federal military entity to enforce civilian law, but if those two SF Groups are state owned anyway, wouldn't that circumvent that requirement, allowing a Governor to send in well trained professional soldiers?
I did a search of this site and Google, looking for the terms Posse Comitatus, 19th Group, terrorism, etc, but didn't find anything I was looking for. Do any of you QP's or LEO's have any thoughts on the use the 19th and 20th Groups in domestic anti-terrorism efforts, the legality of such, or the feasibility of such an option?